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Chiranthodendron pentadactylon . Transverse section series of floral bud from the base to the apex, upper part of perianth organs not shown; vasculature of gynoecium not shown, vasculature of androecium shaded. A Level below perianth insertion. B – D Level of perianth insertion. E Level just below free androecial tube. F – H Level of androecial tube. I Level of androecial lobes. Scale bar = 1 mm
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Androecial development and structure as well as floral vasculature of six selected species of Bombacoideae and of several
smaller lineages of the Malvatheca clade (Malvaceae s.l.) were studied. All studied taxa share a similar pattern of androecial
development: initially, five antepetalous/antetepalous and five alternipetalous/alternitepalous prima...
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... basic pattern of androecium vascular- ization is best described beginning at the level of the androecial tube, where 20 (16 in tetramerous flowers) vascular strands are pres- ent ( Fig. 3D-F). In the alternitepalous posi- tions and most centrally, five main vascular bundles are present (Fig. 3E, F), which distally extend into the tips of the androecial lobes (Fig. 3I). In the floral base, they first merge with the gynoecium vascular complex (Fig. 3A). The 15 (twelve in tetramerous flowers) additional vascular bundles ...
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... basic pattern of androecium vascular- ization is best described beginning at the level of the androecial tube, where 20 (16 in tetramerous flowers) vascular strands are pres- ent ( Fig. 3D-F). In the alternitepalous posi- tions and most centrally, five main vascular bundles are present (Fig. 3E, F), which distally extend into the tips of the androecial lobes (Fig. 3I). In the floral base, they first merge with the gynoecium vascular complex (Fig. 3A). The 15 (twelve in tetramerous flowers) additional vascular bundles present at the level of the androecial tube are arranged in groups of three, each representing an antetepalous ...
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... of androecium vascular- ization is best described beginning at the level of the androecial tube, where 20 (16 in tetramerous flowers) vascular strands are pres- ent ( Fig. 3D-F). In the alternitepalous posi- tions and most centrally, five main vascular bundles are present (Fig. 3E, F), which distally extend into the tips of the androecial lobes (Fig. 3I). In the floral base, they first merge with the gynoecium vascular complex (Fig. 3A). The 15 (twelve in tetramerous flowers) additional vascular bundles present at the level of the androecial tube are arranged in groups of three, each representing an antetepalous androecial sector (Fig. 3D-F). Distally, the central and most peripheral ...
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... tube, where 20 (16 in tetramerous flowers) vascular strands are pres- ent ( Fig. 3D-F). In the alternitepalous posi- tions and most centrally, five main vascular bundles are present (Fig. 3E, F), which distally extend into the tips of the androecial lobes (Fig. 3I). In the floral base, they first merge with the gynoecium vascular complex (Fig. 3A). The 15 (twelve in tetramerous flowers) additional vascular bundles present at the level of the androecial tube are arranged in groups of three, each representing an antetepalous androecial sector (Fig. 3D-F). Distally, the central and most peripheral of these three bundles ends close to the sinus between two neighbouring androecial ...
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... distally extend into the tips of the androecial lobes (Fig. 3I). In the floral base, they first merge with the gynoecium vascular complex (Fig. 3A). The 15 (twelve in tetramerous flowers) additional vascular bundles present at the level of the androecial tube are arranged in groups of three, each representing an antetepalous androecial sector (Fig. 3D-F). Distally, the central and most peripheral of these three bundles ends close to the sinus between two neighbouring androecial lobes (Fig. 3G, H). The two lateral bundles each serve one theca of two neighbouring androe- cium lobes (Figs. 3H, I). In other words, each androecial lobe receives vasculature from two neighbouring antetepalous ...
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... 3A). The 15 (twelve in tetramerous flowers) additional vascular bundles present at the level of the androecial tube are arranged in groups of three, each representing an antetepalous androecial sector (Fig. 3D-F). Distally, the central and most peripheral of these three bundles ends close to the sinus between two neighbouring androecial lobes (Fig. 3G, H). The two lateral bundles each serve one theca of two neighbouring androe- cium lobes (Figs. 3H, I). In other words, each androecial lobe receives vasculature from two neighbouring antetepalous androecial sectors. Proximally, in the perianth/androecium tube, the central of the three bundles merges with the two lateral ones (Fig. 3C). ...
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... the androecial tube are arranged in groups of three, each representing an antetepalous androecial sector (Fig. 3D-F). Distally, the central and most peripheral of these three bundles ends close to the sinus between two neighbouring androecial lobes (Fig. 3G, H). The two lateral bundles each serve one theca of two neighbouring androe- cium lobes (Figs. 3H, I). In other words, each androecial lobe receives vasculature from two neighbouring antetepalous androecial sectors. Proximally, in the perianth/androecium tube, the central of the three bundles merges with the two lateral ones (Fig. 3C). The resulting com- mon bundle merges directly with the perianth vascular complex (Fig. 3A) before ...
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... lobes (Fig. 3G, H). The two lateral bundles each serve one theca of two neighbouring androe- cium lobes (Figs. 3H, I). In other words, each androecial lobe receives vasculature from two neighbouring antetepalous androecial sectors. Proximally, in the perianth/androecium tube, the central of the three bundles merges with the two lateral ones (Fig. 3C). The resulting com- mon bundle merges directly with the perianth vascular complex (Fig. 3A) before joining the gynoecium/androecium vascular complex in the floral base (not shown, see ...
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... cium lobes (Figs. 3H, I). In other words, each androecial lobe receives vasculature from two neighbouring antetepalous androecial sectors. Proximally, in the perianth/androecium tube, the central of the three bundles merges with the two lateral ones (Fig. 3C). The resulting com- mon bundle merges directly with the perianth vascular complex (Fig. 3A) before joining the gynoecium/androecium vascular complex in the floral base (not shown, see ...
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... (1966). However, we could not confirm his observa- Androecium vasculature. In all species studied here, the sterile area of the androecial lobe is supplied by one vascular bundle that branches directly from the central vascular cylinder in the floral base and runs to the distal part of the androecial lobe without supplying any androecial units (Fig. 13A-E). These bundles may branch in the distal-most portion of the androecial lobe as in Gyran- thera (Fig. 13C). The androecial units of each antepetalous/antetepalous androecial sector are supplied by one main vascular bundle that splits into two lateral bundles before entering the two half-sectors ( Fig. 13A-E). In Ochroma and Patinoa each ...
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... sterile area of the androecial lobe is supplied by one vascular bundle that branches directly from the central vascular cylinder in the floral base and runs to the distal part of the androecial lobe without supplying any androecial units (Fig. 13A-E). These bundles may branch in the distal-most portion of the androecial lobe as in Gyran- thera (Fig. 13C). The androecial units of each antepetalous/antetepalous androecial sector are supplied by one main vascular bundle that splits into two lateral bundles before entering the two half-sectors ( Fig. 13A-E). In Ochroma and Patinoa each lateral bundle Fig. 11. Patinoa sphaerocarpa. Androecium development and structure. A Differentiation of ...
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... without supplying any androecial units (Fig. 13A-E). These bundles may branch in the distal-most portion of the androecial lobe as in Gyran- thera (Fig. 13C). The androecial units of each antepetalous/antetepalous androecial sector are supplied by one main vascular bundle that splits into two lateral bundles before entering the two half-sectors ( Fig. 13A-E). In Ochroma and Patinoa each lateral bundle Fig. 11. Patinoa sphaerocarpa. Androecium development and structure. A Differentiation of structures derived from central alternipetalous primary androecial primordia into sterile areas and the two neighbouring structures derived from antepetalous primary androecial primordia into androecial ...
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... androecial tips of androecial lobes. Abbreviations: al androecial lobe; at tip of androecial lobe; 2° ap secondary androecial primordium, p petal. Scale bars: A-D = 0.1 mm; E = 0.5 mm further subdivides into two strands, one supplying the more basally placed u-shaped androecial unit, the other one the distally placed elongate androecial unit (Fig. 13D, E). In the distal portion, each lateral bundle gives rise to several smaller bundles that supply different portions of the elongate androecial unit. In contrast to Fremontodendron, in Chiranthodendron a smaller bundle branches from one of the lateral bundles and ends in the distal portion of the androecial tube between the two ...
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... distal portion, each lateral bundle gives rise to several smaller bundles that supply different portions of the elongate androecial unit. In contrast to Fremontodendron, in Chiranthodendron a smaller bundle branches from one of the lateral bundles and ends in the distal portion of the androecial tube between the two neighbouring androecial lobes (Fig. 13A). A similar bundle is also found in Gyranthera, but there it supplies androecial units situated on the androecial tube between the two neighbouring androecial lobes (Fig. 13C). In most genera the main vascular bundle of the antepetalous/antetepa- lous sector branches from the petal bundle. In Fremontodendron and Patinoa, however, the ...
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... a smaller bundle branches from one of the lateral bundles and ends in the distal portion of the androecial tube between the two neighbouring androecial lobes (Fig. 13A). A similar bundle is also found in Gyranthera, but there it supplies androecial units situated on the androecial tube between the two neighbouring androecial lobes (Fig. 13C). In most genera the main vascular bundle of the antepetalous/antetepa- lous sector branches from the petal bundle. In Fremontodendron and Patinoa, however, the main antepetalous/antetepalous vascular bun- dle has its origin further down in the floral base, where it emerges directly from the central vascular ...
Citations
... En detalle, fue posible observar que en el extremo distal de los filamentos estaminales de T. cacao se localiza una masa de tejido arquespórico que se diferenciará para la formación de las células madre de las microsporas y los tejidos vegetativos que formaran la antera madura que para el momento de la dehiscencia solo persiste la epidermis y el endotecio; todo el patrón histológico observado, es similar en estructura y función al descrito previamente en Malvaceae y en la mayoría de las angiospermas, situación que muestra un amplio grado de uniformidad ontogenética de este proceso en plantas (Fernández et al., 2015;Lattar et al., 2012;Lattar et al., 2014;Rincón-Barón et al., 2021b;Scott et al., 2004;Tang et al., 2006;von Balthazar et al., 2006). En algunas especies de Malvaceae se ha registrado la presencia de tapete invasivo no sincitial, además del plasmodial (Galati et al., 2007;Galati et al., 2011;Lattar et al., 2014;Rincón-Barón et al., 2021b;Strittmatter et al., 2000;Tang et al., 2009); aunque el tapete secretor es el más común en esta familia (Lattar et al., 2014;Tang et al., 2006) en ambos casos, el tapete degenera en el momento de la liberación de los granos de polen, situación que se pudo apreciar con el tapete secretor en esta investigación para T. cacao. ...
Introducción:
No conocemos estudios sobre la microsporogénesis de la planta de cacao, y poco se sabe sobre la ultraestructura de sus granos de polen.
Objetivo:
Describir la microsporogénesis y ultraestructura de los granos de polen en T. cacao.
Métodos:
Procesamos más de 30 flores para cada etapa floral, teñidas con Safranina-Azul Alcian, PAS-Amidoblack y Lacmoid. Para la microscopía de transmisión procesamos las muestras en resina y las teñimos con azul de toluidina. Para microscopía electrónica de barrido, fijamos y deshidratamos en 2.2-dimetoxipropano, secamos hasta un punto crítico y recubrimos con oro.
Resultados:
Anteras diferenciadas por una masa celular en los extremos distales a los filamentos estaminales. Durante el desarrollo la pared de las anteras presenta varios estratos celulares y al madurar se reducen a la epidermis y al endotecio. Las células madre de microsporas se dividen por meiosis para formar tétradas. El tapete es secretor e intacto hasta que se liberan los granos, para luego degenerar. Los granos de polen son isopolares, esferoidales, pequeños, tricolpados. La ultraestructura presenta una esporodermis semitectada, con ornamentación reticulada, y un retículo heterobrochado con el muri sin ornamentación. La exina se deposita antes que la intina. Los orbículos son individuales, lisos y de tamaño variado. Hay abundante polenkit en el tectum y entre las columelas. La intina es delgada, pero se desarrolla ampliamente en las áreas del colpo, formando una intina interna compacta y una intina externa inusual con una apariencia columelada.
Conclusión:
La estructura y el desarrollo de las anteras siguen el patrón de las angiospermas. La microsporogénesis simultánea y la deposición centrípeta de la esporodermis se conocen de Malvaceae, pero los caracteres de la intina son nuevos para la familia.
... At the species level, differences in pollinator abundance and frequency of visits across a range have been shown to drive intraspecific variation in floral traits (Johnson, 1997), showing that such polymorphism could serve as a precursor to species divergence. Indeed, it is becoming increasingly appreciated that geographic and local variation in floral traits and pollinator visitation rates is common, especially in Within Bombacoideae (Malvaceae), multiple evolutionary shifts between mammalian and hawkmoth pollination have been inferred (Fleming et al., 2009;von Balthazar et al., 2006), including at least two transitions within Adansonia itself (Baum et al., 1998;Karimi et al., 2019). This lability partly reflects the fact that the nocturnal, nectar-rich flowers of baobabs may attract both bats and hawkmoths. ...
Chiropterophily, or bat pollination, is typically considered a highly specialized pollination system that has evolved independently numerous times across the angiosperm phylogeny, with distinct lineages often converging on a similar suite of floral traits. The African baobab, Adansonia digitata, occurs widespread across continental Africa and introduced throughout much of the tropics, possesses floral traits classically associated with bat pollination, namely nocturnal anthesis, pendulous white flowers, and a “musky” fragrance. Despite this, our observations and pollination exclusion experiments in South African baobab populations suggested little if any role for bats, but instead showed that hawkmoths are the main pollinators. Hand pollination indicated strong self‐incompatibility and crossing experiments suggest minimal diurnal receptivity. Furthermore, our analyses of floral volatiles revealed not only sulfur‐containing compounds, commonly associated with bat pollination, but also a high concentration of the sesquiterpene β‐caryophyllene, a compound generally more typical of hawkmoth pollination. Comparing previous pollination studies and published floral scent profiles from West Africa suggests that the classic bat pollination system in baobabs may be more labile than previously thought. This study provides an empirical example of a species that most likely evolved due to bat pollination yet has some degree of generality and possible geographic variation in floral traits and pollinator visitation patterns across its range. Baobabs have long been recognized as being bat‐pollinated. However, in the absence of bats, hawkmoths are the primary pollinators in some populations, suggesting geographic variation in pollinator visitation rates across Africa, possibly driven by differences in floral scent.
... En Malvaceae se ha indicado la formación de primordios androeciales en el meristemo floral que por crecimiento y diferenciación celular determinan la formación de la columna estaminal del andróforo y los filamentos estaminales (Von Balthazar et al., 2006). Estos filamentos presentan en sus ápices una masa de tejido arquespórico que se diferenciará para la formación de las células madre de las microsporas (Scott et al., 2004;Von Balthazar et al., 2006;Fernández et al., 2015), en A. rosea se observó una situación similar, lo que implicaría cierto grado de uniformidad ontogenética en el desarrollo y formación de estas estructuras. ...
... En Malvaceae se ha indicado la formación de primordios androeciales en el meristemo floral que por crecimiento y diferenciación celular determinan la formación de la columna estaminal del andróforo y los filamentos estaminales (Von Balthazar et al., 2006). Estos filamentos presentan en sus ápices una masa de tejido arquespórico que se diferenciará para la formación de las células madre de las microsporas (Scott et al., 2004;Von Balthazar et al., 2006;Fernández et al., 2015), en A. rosea se observó una situación similar, lo que implicaría cierto grado de uniformidad ontogenética en el desarrollo y formación de estas estructuras. La diferenciación y desarrollo de las anteras de A. rosea muestra un patrón histológico característico de la mayoría de las Malvaceae (Tang et al., 2006;Lattar et al., 2012;Lattar et al., 2014), que implica la formación de pared de las anteras y células madre de las microsporas a partir de derivados celulares del tejido arquespórico; además, la pared de las anteras inicialmente está constituida de una sola capa celular y luego a medida que ésta madura se forman varios estratos celulares y al momento de la dehiscencia solo persiste la epidermis y el endotecio. ...
Introducción:
Los estudios sobre microsporogénesis, micromorfología y estructura de los granos de polen en Malvaceae son escasos.
Objetivos:
Describir el proceso de microsporogénesis y aspectos micromorfológicos de los granos de polen en A. rosea.
Métodos:
Se procesaron más de 30 andróforos de acuerdo con los protocolos estándar para incrustar y seccionar en parafina. Las secciones obtenidas se tiñeron con Azul de Safranina-Alcian, las anteras inmaduras y no fijadas se tiñeron con Azul de anilina. Se procesaron secciones de resina adicionales de los andróforos y se tiñeron con azul de toluidina. Se observaron secciones ultrafinas con microscopía electrónica de transmisión (MET). Para la observación con microscopía electrónica de barrido (MEB), el material se fijó y deshidrató en 2,2 dimetoxipropano, luego se secó hasta un punto crítico y se recubrieron con oro.
Resultados:
las anteras se diferencian de una masa celular en los extremos distales de los filamentos del estambre. La pared de la antera madura presenta una capa externa de células epidérmicas y una capa interna, el endotecio. Las células madre de microesporas se dividen por mitosis y luego experimentan meiosis para formar tétradas. El tapete es inicialmente celular y forma una sola capa de células y luego pierde integridad celular al invadir el lóculo de microsporangio, formando un periplasmodio. Durante la formación de la esporodermis, primero se deposita la exina y luego la intina. Para el momento de la liberación de los granos de polen, el tapete se ha degenerado por completo. Los granos de polen son pantoporados, apolares, con simetría radial, esferoidales, con espinas, báculas, gránulos y microgránulos. El téctum está perforado con fovéoleas dispuestas homogéneamente en toda la superficie y con polenkit. La exina es ancha (5-6 µm) y consta de una endexina gruesa de 3.5 a 4 µm y una ektexina fina (0.6-0.7 µm). La ultraestructura muestra columelas claramente definidas formando el infratéctum. Se aprecian tricomas nectaríferos unicelulares glandulares capitados (TG) cubriendo toda la superficie de los filamentos de los estambres.
Conclusiones:
La estructura y desarrollo de las anteras sigue los patrones conocidos de las angiospermas. La microsporogénesis simultánea y el depósito centrípeto de la esporodermis se han descrito previamente para Malvaceae.
... Bombacaceae, Sterculiaceae, Tiliaceae and Malvaceae. It also consists of 245 genera and 4300 species distributed throughout the world especially in the tropics (1,2). The subfamily Sterculioideae Beilschm., designated earlier as Sterculiaceae (DC) Bartl., is a monophyletic group having four major clades of which genus Sterculia L. belongs to the clade Sterculia (3). ...
Sterculia striatiflora Mast, a rarely known species of Malvaceae s.l., is reported here as a new distribution record and addition to the Flora of Assam, India. A detailed description, colour photographs and other relevant information has been provided for its identification.
... Anthers with transversely septate locules (in most species modified to 1-loculed half-anthers) were indicated as synapomorphy in some studies (e.g., Judd et al. 2008), but this character is likely homoplasious in /Malvatheca (Le Pé chon and Gigord 2014). Le Pé chon and Gigord (2014) indicate that the aspects of the androecial development as described in detail by von Balthazar et al. (2004Balthazar et al. ( , 2006 may be synapomorphic, and Stevens (2001) additionally indicates the absence of a root hypodermis and stamen filaments forming a tube as potential synapomorphies (Figure 3). /Bombacoideae are characterized by palmately compound leaf laminas, the triangular, nonspiny pollen, a unique chromosome number (n ¼ 36), embryo morphology, seed anatomy and the absence of mucilaginous substances (Fuchs 1967;Hutchinson 1967;Fryxell 1968;Singh and Chauhan 1984;Baum and Oginuma 1994;El Naggar 2001;Bayer and Kubitzki 2003;Takhtajan 2009). ...
Malvaceae s.l., the most diverse family within Malvales, includes well-known species of great economic importance like cotton, cacao, and durian. Despite numerous phylogenetic analyses employing multiple markers, relationships between several of its nine subfamilies, particularly within the largest lineage/Malvadendrina, remain unclear. In this study, we attempted to resolve the relationships within the major clades of Malvaceae s.l. using plastid genomes of 48 accessions representing all subfamilies. Maximum likelihood and Bayesian analyses recovered a fully resolved and well-supported topology confirming the split of the family into/Byttneriina (/Grewioideae +/Byttnerioideae) and/Malvadendrina. Within/Malvadendrina,/Helicteroideae occupied the earliest branching position, followed by/Sterculioideae./Brownlowioideae,/Tiliodeae, and/Dombeyoideae formed a clade sister to/Malvatheca (/Malvoideae +/Bombacoideae), a grouping morphologically supported by the lack of androgynophore. Results from dating analyses suggest that all subfamilies originated during hot or warm phases in the Late Cretaceous to Paleocene. This study presents a well-supported phylogenetic framework for Malvaceae s.l. that will aid downstream revisions and evolutionary studies of this economically important plant family.
... Particularly, in Malvoideae and Bombacoideae (Malvatheca clade), the flowers form an androecial tube around the style (Van Heel 1966;von Balthazar et al. 2004) rather than forming a synandrium as in Bdallophytum. The androecium of Bdallophytum is more similar to those of the species of the clade Malvatheca, in which the androecial tube formed by the fused filaments has sessile monothecal anthers (von Balthazar et al. 2006). An additional trait in the androecium is the apical extension of the anther connective tissue in B. americanum, which is less conspicuous in B. andrieuxii. ...
Cytinaceae are root endoparasitic plants with only three genera. Their biology is largely unknown, and most knowledge of the family is based on the Old World genus, Cytinus. Here, we studied all three species of the New World Bdallophytum from Mexico. We describe their morphoanatomy, floral development, and embryology, highlighting the unique traits of Bdallophytum compared with two other genera of the family and members of Malvales. Both B. americanum and B. andrieuxii are dioecious, while B. oxylepis is gynomonoecious. The floral size and the number of floral organs vary within and among species, which appears common in Cytinaceae. The flowers of Bdallophytum exhibit synorganization in sexual organs, a synandrium in male flowers, and a gynostemium in bisexual flowers of B. oxylepis. Unisexual and bisexual flowers are zygomorphic at the early developmental stages. The unisexual flowers become actinomorphic in later development, while the bisexual flowers of B. oxylepis remain zygomorphic. The androecium of Bdallophytum has key traits shared with some Malvales, such as the fused filaments in Malvaceae and Sarcolaenaceae and the connective appendage shared with Dipterocarpaceae. Our results suggest that a unitegmic ovule is a unique trait for Bdallophytum. This is proposed here as a putative synapomorphy for Bdallophytum.
... For example, the presence of bracts, also called epicalyx or leaf-like, surrounding the sepals is observed in Gossypium species, as shown here in G. hirsutum flower buds (Fig. 1e, i, j) (Ritchie et al. 2007;Tan et al. 2013), as well as in T. cacao (Swanson et al. 2008) and H. syriacus (Kouchi 1988;Takahashi and Kouchi 2006). Other taxa of the Malvatheca clade (Bombacoideae and Malvoideae) such as Chiranthodendron pentadactylon, Fremontodendron californicum, Gyranthera caribensis and Huberodendron swietenioides, also develop bracts (Balthazar et al. 2006). In addition, pollen grains present echinate ornamentation, a common characteristic of cotton, which is demonstrated here in G. hirsutum (Fig. 3h, i) and has also been observed in Malvaceae members, such as T. cacao (Swanson et al. 2008) and H. syriacus (Kouchi 1988;Takahashi and Kouchi 2006;Swanson et al. 2008;Wu et al. 2015). ...
Gossypium hirsutum is the most important cotton species that is cultivated worldwide. Although cotton reproductive
development is important for fiber production, since fiber is formed on the epidermis of mature ovules, cotton floral development
remains poorly understood. Therefore, this work aims to characterize the cotton floral morphoanatomy by performing
a detailed description of anther and ovule developmental programs and identifying stage-specific floral marker genes in G.
hirsutum. Using light microscopy and scanning electron microscopy, we analyzed anther and ovule development during 11
stages of flower development. To better characterize the ovule development in cotton, we performed histochemical analyses to
evaluate the accumulation of phenolic compounds, pectin, and sugar in ovule tissues. After identification of major hallmarks
of floral development, three key stages were established in G. hirsutum floral development: in stage 1 (early—EF), sepal,
petal, and stamen primordia were observed; in stage 2 (intermediate—IF), primordial ovules and anthers are present, and
the differentiating archesporial cells were observed, marking the beginning of microsporogenesis; and in stage 6 (late—LF),
flower buds presented initial anther tapetum degeneration and microspore were released from the tetrad, and nucellus and
both inner and outer integuments are developing. We used transcriptome data of cotton EF, IF and LF stages to identify floral
marker genes and evaluated their expression by real-time quantitative PCR (qPCR). Twelve marker genes were preferentially
expressed in a stage-specific manner, including the putative homologs for AtLEAFY, AtAPETALA 3, AtAGAMOUS-LIKE 19
and AtMALE STERILITY 1, which are crucial for several aspects of reproductive development, such as flower organogenesis
and anther and petal development. We also evaluated the expression profile of B-class MADS-box genes in G. hirsutum
floral transcriptome (EF, IF, and LF). In addition, we performed a comparative analysis of developmental programs between
Arabidopsis thaliana and G. hirsutum that considered major morphoanatomical and molecular processes of flower, anther,
and ovule development. Our findings provide the first detailed analysis of cotton flower development.
... Several studies tend to support this assumption (e.g. Caris 2013;Hufford 1990Hufford , 1995Hufford , 1998Jabbour et al. 2009;Olson 2003;van Heel 1966;Vasconcelos et al. 2017;von Balthazar et al. 2006;Zhao et al. 2012). However, while this criterion is supported in some families, such as Myrtaceae, it is not absolute, as other families show a strong lability in early development, while they are much more stable at later developmental stages (e.g. ...
... Strongly monosymmetric flowers generally show a unidirectional initiation sequence of floral organs, with the first organs arising in areas with least pressure, either adaxially or abaxially. Flowers with an elliptical shape develop in a variety of groups with variable causes, such as Eupteleaceae (Ren et al. 2007), Buxaceae (von Balthazar et al. 2006), Winteraceae (Doust 2001(Doust , 2002Doust and Drinnan 2004), Bataceae ( Fig. 4a; Ronse De Craene 2005); Rubiaceae (Rutishauser et al. 1998); Begoniaceae, or Papaveraceae (Ronse De Craene and Smets 1990; Fig. 1a, b). Pressures are strongest on lateral flowers in compound inflorescences, leading to elliptical shapes and a dimorphism between lateral and terminal flowers (e.g. ...
Flower morphology results from the interaction of an established genetic program, the influence of external forces induced by pollination systems, and physical forces acting before, during and after initiation. Floral ontogeny, as the process of development from a meristem to a fully developed flower, can be approached either from a historical perspective, as a "recapitulation of the phylogeny" mainly explained as a process of genetic mutations through time, or from a physico-dynamic perspective, where time, spatial pressures, and growth processes are determining factors in creating the floral morphospace. The first (historical) perspective clarifies how flower morphology is the result of development over time, where evolutionary changes are only possible using building blocks that are available at a certain stage in the developmental history. Flowers are regulated by genetically determined constraints and development clarifies specific transitions between different floral morphs. These constraints are the result of inherent mutations or are induced by the interaction of flowers with pollinators. The second (physico-dynamic) perspective explains how changes in the physical environment of apical meristems create shifts in ontogeny and this is reflected in the morphospace of flowers. Changes in morphology are mainly induced by shifts in space, caused by the time of initiation (heterochrony), pressure of organs, and alterations of the size of the floral meristem, and these operate independently or in parallel with genetic factors. A number of examples demonstrate this interaction and its importance in the establishment of different floral forms. Both perspectives are complementary and should be considered in the understanding of factors regulating floral development. It is suggested that floral evolution is the result of alternating bursts of physical constraints and genetic stabilization processes following each other in succession. Future research needs to combine these different perspectives in understanding the evolution of floral systems and their diversification.
... (e.g., Bakhuizen van den Brink, 1924;Barroso et al., 2002). Such a broadened circumscription of Adansonieae makes the tribe rather variable in flower traits: Ceiba and Spirotheca have five stamens with two or four thecae each (Gibbs and Alverson, 2006;Gibbs and Semir, 2003); whereas Bernoullia and Gyranthera have anthers with many distal, sessile thecae on an elongated staminal tube (von Balthazar et al., 2006). Furthermore, Bernoullia and Gyranthera exhibit distinct capsular fruits enclosing winged seeds that differ from the woody berries of Adansonia and from the capsules with kapok and non-winged seeds of Ceiba and most other Adansonieae genera. ...
... Species in the Winged seed clade also share staminal filaments that are completely connate bearing distal, sessile, ''polythecate" anthers (i.e., with many sessile thecae on an elongated staminal tube), though this may be plesiomorphic for the Malvatheca clade (i.e., Malvoideae + Bombacoideae) (von Balthazar et al., 2006). Representatives of the Winged seed clade also have subaggregate wood parenchyma, with very narrow lines regularly alternating with 2-4 tangential rows of fibers that may extend from ray to ray, in cross section, mostly small flowers (ca. ...
Bombacoideae (Malvaceae) is a clade of deciduous trees with a marked dominance in many forests, especially in the Neotropics. The historical lack of a well-resolved phylogenetic framework for Bombacoideae hinders studies in this ecologically important group. We reexamined phylogenetic relationships in this clade based on a matrix of 6,465 nuclear (ETS, ITS) and plastid (matK, trnL-trnF, trnS-trnG) DNA characters. We used maximum parsimony, maximum likelihood, and Bayesian inference to infer relationships among 108 species (∼70% of the total number of known species). We analysed the evolution of selected morphological traits: trunk or branches prickles, calyx shape, endocarp type, seed shape, and seed number per fruit, using ML reconstructions of their ancestral states to identify possible synapomorphies for major clades. Novel phylogenetic relationships emerged from our analyses, including three major lineages marked by fruit or seed traits: the winged-seed clade (Bernoullia, Gyranthera, and Huberodendron), the spongy endocarp clade (Adansonia, Aguiaria, Catostemma, Cavanillesia, and Scleronema), and the Kapok clade (Bombax, Ceiba, Eriotheca, Neobuchia, Pachira, Pseudobombax, Rhodognaphalon, and Spirotheca). The Kapok clade, the most diverse lineage of the subfamily, includes sister relationships (i) between Pseudobombax and “Pochota fendleri” a historically incertae sedis taxon, and (ii) between the Paleotropical genera Bombax and Rhodognaphalon, implying just two bombacoid dispersals to the Old World, the other one involving Adansonia. This new phylogenetic framework offers new insights and a promising avenue for further evolutionary studies. In view of this information, we present a new tribal classification of the subfamily, accompanied by an identification key.
... Hermannia, Melochia: van Heel, 1966). The origin of the diversity in androecial configurations in Malvaceae is complex (see van Heel, 1966;von Balthazar et al., 2006;Ronse De Craene, 2010). However, a common feature is a triplet arrangement consisting of an outer alternisepalous stamen pair and a single inner antesepalous stamen. ...
... Primary obdiplostemony type I is far less common among core eudicots, as it is mainly concentrated in Malvaceae (and possibly in Euphorbiaceae), where antesepalous stamens become typically reduced and lost, and alternisepalous stamens are duplicated or proliferate (e.g. von Balthazar et al., 2006). The androecium in Malvaceae represents a unique obdiplostemonous bauplan (see also Venkata Rao, 1949, 1952van Heel, 1966), and von Balthazar et al. (2006) consider this to be plesiomorphic for Malvaceae. ...
... von Balthazar et al., 2006). The androecium in Malvaceae represents a unique obdiplostemonous bauplan (see also Venkata Rao, 1949, 1952van Heel, 1966), and von Balthazar et al. (2006) consider this to be plesiomorphic for Malvaceae. In all investigated cases alternisepalous stamens emerge externally to the antesepalous stamens. ...
Background and aims:
Obdiplostemony has long been a controversial condition as it diverges from diplostemony found among most core eudicot orders by the more external insertion of the alternisepalous stamens. In this paper we review the definition and occurrence of obdiplostemony, and analyse how the condition has impacted on floral diversification and species evolution.
Key results:
Obdiplostemony represents an amalgamation of at least five different floral developmental pathways, all of them leading to the external positioning of the alternisepalous stamen whorl within a two-whorled androecium. In secondary obdiplostemony the antesepalous stamens arise before the alternisepalous stamens. The position of alternisepalous stamens at maturity is more external due to subtle shifts of stamens linked to a weakening of the alternisepalous sector including stamen and petal (type I), alternisepalous stamens arisingde factoexternally of antesepalous stamens (type II) or alternisepalous stamens shifting outside due to the sterilization of antesepalous stamens (type III: Sapotaceae). In primary obdiplostemony the alternisepalous stamens arise before the antesepalous stamens and are more externally from initiation. The antesepalous stamen whorl is staminodial and shows a tendency for loss (type I), or the petals are missing and the alternisepalous stamens effectively occupy their space (type II). Although obdiplostemony is often related to an isomerous gynoecium, this is not essential. Phylogenetically, both secondary and primary obdiplostemony can be seen as transitional stages from diplostemony to either haplostemony or obhaplostemony. Obdiplostemony is the consequence of shifts in the balance between the two stamen whorls, affecting either the alternisepalous stamens together with the petals, or the antesepalous stamens.
Conclusions:
We advocate a broad definition of obdiplostemony, to include androecia with incomplete whorls, staminodial whorls, anisomerous gynoecia and an absence of petals. As such, the taxonomic significance of obdiplostemony is transient, although it is a clear illustration of how developmental flexibility is responsible for highly different floral morphs.
