Morphology of multicellular structures with stomata in Cuscuta (scanning electron microscopy). ((A) and (B)) Stems. (A) Extrafloral nectary (EN) in C. reflexa. (B) Stomatiferous protuberances (SPs) on C. bonafortunae haustorial stem. ((C)?(U)) Flowers. ((C) and (D)) ENs on calyx of C. japonica. ((E) and (F)) Regular stomata on corolla lobes of C. japonica. ((G)?(I)) Floral SPs in subg. Cuscuta. (G) Calyx, C. approximata. ((H) and (I)) Calyx lobe terminal SP in C. epithymum. (J) Floral SPs at base of calyx in subg. Pachystigma (C. africana). ((L)? (U)) Floral SPs in subg. Grammica. (L) Dome-like SP on calyx of C. strobillacea. ((L)?(M)) Conical SPs on calyx and corolla lobes, respectively, of C. chapalana. ((N) and (O)) Cylindrical SPs on calyx lobes of C. boldinghii. (P) Conical SP on calyx lobe of C. warneri. ((R) and (S)) Crest-like SPs on calyx lobes of C. cotijana. (R) Flower bud stage. (S) Fully grown calyx lobe. (T) Crest-like SP on C. iguanella calyx lobe. (U) Crest-like SP on C. alata corolla lobe. Arrowheads indicate the position of SPs. Scale bars: (A), (B), (D), (K), (O) = 100 m; (C), (G), (E), (J), (R), (S) = 1 mm; (I), (F) = 50 m; (H), (L), (M), (N), (P), (T) = 0.5 mm.  

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... 1; Fig. S1). Vegetative plants form mostly exploratory or foraging stems, which like the Cuscuta type have a smooth appearance because they lack SPs. During flowering and fruiting, haustorial stems (attached to the host through haustoria; Fig. S1) change drastically and acquire a "rough" appearance because numerous SPs (20-30/mm −2 ) form on them (Fig. 2B). Stem SPs of subg. Grammica are conical or dome-like, 0.1-0.3 mm long, usually with one distal stoma (Fig. 2B). Exploratory stems constitute most of the vegetative body of Grammica species; however, exploratory stems disappear gradually during flowering and fruiting when they are replaced by haustorial stems (Fig. S1). Subgenus Cus- ...

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... appearance because they lack SPs. During flowering and fruiting, haustorial stems (attached to the host through haustoria; Fig. S1) change drastically and acquire a "rough" appearance because numerous SPs (20-30/mm −2 ) form on them (Fig. 2B). Stem SPs of subg. Grammica are conical or dome-like, 0.1-0.3 mm long, usually with one distal stoma (Fig. 2B). Exploratory stems constitute most of the vegetative body of Grammica species; however, exploratory stems disappear gradually during flowering and fruiting when they are replaced by haustorial stems (Fig. S1). Subgenus Cus- cuta stems and the exploratory stems of Grammica have very low densities of 'normal' stomata (typically <1 mm −2 ...

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... Grammica species; however, exploratory stems disappear gradually during flowering and fruiting when they are replaced by haustorial stems (Fig. S1). Subgenus Cus- cuta stems and the exploratory stems of Grammica have very low densities of 'normal' stomata (typically <1 mm −2 ; Fig. 1). Stem SP stomata are smaller than the EN stomata, 16-28 m long (Fig. ...

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... states (Table 1) and their distribution in the entire genus are summarized in Table S1. ENs are common on the calyx lobe midveins of Monogynella species (Fig. 2C-D), and they resemble morphologically the ENs present on the stems. Infre- quently, stomata may also occur on the corolla of Monogynella species, but these stomata likely do not have a secretory role ( Fig. 2E and ...

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... and their distribution in the entire genus are summarized in Table S1. ENs are common on the calyx lobe midveins of Monogynella species (Fig. 2C-D), and they resemble morphologically the ENs present on the stems. Infre- quently, stomata may also occur on the corolla of Monogynella species, but these stomata likely do not have a secretory role ( Fig. 2E and ...

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... SPs are ubiquitous in subgenera Cuscuta and Pachystigma, either on the calyx and corolla (subg. Cuscuta; Fig. 2G-I; Fig. S2B-F) or only on the calyx (subg. Pachystigma; Fig. 2J). In contrast, in subg. Grammica floral SPs have evolved only in 24 species (see below). In the latter subgenus, floral SPs are similar morphologically to SPs found on their haustorial stems but they are larger, 0.2-1 mm long, and bear up to 10 stomata ( Fig. 2K-U). This increased ...

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... SPs are ubiquitous in subgenera Cuscuta and Pachystigma, either on the calyx and corolla (subg. Cuscuta; Fig. 2G-I; Fig. S2B-F) or only on the calyx (subg. Pachystigma; Fig. 2J). In contrast, in subg. Grammica floral SPs have evolved only in 24 species (see below). In the latter subgenus, floral SPs are similar morphologically to SPs found on their haustorial stems but they are larger, 0.2-1 mm long, and bear up to 10 stomata ( Fig. 2K-U). This increased complex- ity suggests an additional degree of ...

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... (subg. Cuscuta; Fig. 2G-I; Fig. S2B-F) or only on the calyx (subg. Pachystigma; Fig. 2J). In contrast, in subg. Grammica floral SPs have evolved only in 24 species (see below). In the latter subgenus, floral SPs are similar morphologically to SPs found on their haustorial stems but they are larger, 0.2-1 mm long, and bear up to 10 stomata ( Fig. 2K-U). This increased complex- ity suggests an additional degree of specialization of floral SPs in subg. Grammica. Floral SP stomata in all three subgenera are small, 15-25 m long (Fig. ...

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... the latter subgenus, floral SPs are similar morphologically to SPs found on their haustorial stems but they are larger, 0.2-1 mm long, and bear up to 10 stomata ( Fig. 2K-U). This increased complex- ity suggests an additional degree of specialization of floral SPs in subg. Grammica. Floral SP stomata in all three subgenera are small, 15-25 m long (Fig. ...

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... shape of SPs in subgenera Cuscuta and Pachystigma is termed here "diffuse" because they are usually not as sharply differenti- ated morphologically on the surface of the calyx or corolla as the SPs of subg. Grammica. Stomata are present in fleshy areas of the calyx or corolla lobes ( Fig. 2G-I; Fig. S2B-F). The shape of SPs in subg. Grammica is more diverse, and in general these structures are more obvious morphologically than in subgenera Cuscuta and Pachystigma ( Fig. 2; Fig. S2I-T). The variation of floral SP shape in subg. Grammica includes 3 of the 4 character states defined (Table 1): dome-like, usually with 1(-2) distal stomata, ...

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... ated morphologically on the surface of the calyx or corolla as the SPs of subg. Grammica. Stomata are present in fleshy areas of the calyx or corolla lobes ( Fig. 2G-I; Fig. S2B-F). The shape of SPs in subg. Grammica is more diverse, and in general these structures are more obvious morphologically than in subgenera Cuscuta and Pachystigma ( Fig. 2; Fig. S2I-T). The variation of floral SP shape in subg. Grammica includes 3 of the 4 character states defined (Table 1): dome-like, usually with 1(-2) distal stomata, conical to cylindrical with 2-5 stomata, and crest-like with up to 10 stomata ( Fig. 2; Fig. ...

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... these structures are more obvious morphologically than in subgenera Cuscuta and Pachystigma ( Fig. 2; Fig. S2I-T). The variation of floral SP shape in subg. Grammica includes 3 of the 4 character states defined (Table 1): dome-like, usually with 1(-2) distal stomata, conical to cylindrical with 2-5 stomata, and crest-like with up to 10 stomata ( Fig. 2; Fig. ...

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... SPs in subg. Cuscuta are usually terminal, found at the tips of calyx lobes (Fig. 2); only in Cuscuta europaea several SPs are distributed along the midveins of calyx lobes. Three of the four Pachystigma species examined had SPs at the base of their calyx García et al., 2014). lobes ( Fig. 2J; Table S1). In subg. Grammica, distal SPs are most commonly subterminal ( Fig. 2; Table ...

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... SPs in subg. Cuscuta are usually terminal, found at the tips of calyx lobes (Fig. 2); only in Cuscuta europaea several SPs are distributed along the midveins of calyx lobes. Three of the four Pachystigma species examined had SPs at the base of their calyx García et al., 2014). lobes ( Fig. 2J; Table S1). In subg. Grammica, distal SPs are most commonly subterminal ( Fig. 2; Table ...

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... are usually terminal, found at the tips of calyx lobes (Fig. 2); only in Cuscuta europaea several SPs are distributed along the midveins of calyx lobes. Three of the four Pachystigma species examined had SPs at the base of their calyx García et al., 2014). lobes ( Fig. 2J; Table S1). In subg. Grammica, distal SPs are most commonly subterminal ( Fig. 2; Table ...

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... water uptake experiment done in the field showed that during the day, hosts with leaves parasitized by C. costaricensis absorbed significantly more water than hosts free of the parasite ( Fig. 5A; Table S2), despite the fact that the latter had a higher leaf stomatal conductance than the former ( Fig. 5E; Table S3). Also, after their leaves were removed, stems of parasitized hosts continued to absorb water (Fig. 5B), while non-parasitized hosts had a minimal water uptake (Table S2). During the night, unparasitized hosts with or without ...

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... "diffuse" floral SPs of subgenera Cuscuta and Pachystigma are relatively discrete morphologically compared to those of subg. Grammica ( Fig. 2; Fig. S2). Only in some species, for example Cus- cuta approximata and Cuscuta planiflora, they were described as appendages or fleshy ("turgid") apices of the calyx lobes (e.g., Yuncker, 1932;García, 2011;Fig. 2G;Fig. S2 B and E). In other species, such as Cuscuta epithymum, C. europaea, Cuscuta epilinum, SPs can be observed only with a ...

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... species, for example Cus- cuta approximata and Cuscuta planiflora, they were described as appendages or fleshy ("turgid") apices of the calyx lobes (e.g., Yuncker, 1932;García, 2011;Fig. 2G;Fig. S2 B and E). In other species, such as Cuscuta epithymum, C. europaea, Cuscuta epilinum, SPs can be observed only with a scanning electron microscope ( Fig. 2H-I; Fig. S2 C and D). In subg. Grammica, the presence of floral SPs, their shape and position are homoplastic, however, this is the general situation of other morphological characters both in Gram- mica and Cuscuta more broadly (Welsh et al., 2010;Wright et al., 2011Wright et al., , 2012Riviere et al., 2013;García et al., 2014). Although floral SP ...

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... et al., 2014). Although floral SP characters alone are insufficient to infer phylogenetic relation- ships among sections of subg. Grammica, considering the limited number of floral characters available, the diversity of SPs is impor- tant within each clade at the species level. The fine morphology of SPs is quite unique in many species (Fig. S2I-T), which makes these structures useful in species delimitation as proven by several recent taxonomic revisions (Costea and Stefanoví c, 2009;Costea et al., 2011aCostea et al., ,b, ...