Leaf venation patterns in the genus Saxifraga (Saxifragaceae)

Abstract

Details of leaf venation in 150 species of Saxifraga L. representing all 13 sections are reported. Three main patterns were observed: palinactinodromous, acrodromous and camptodromous. Species with lobed leaves have palinactinodromous patterns, whereas those with entire leaves are acrodromous or camptodromous. Thus species from sections Heterisia, Irregulares, Cymbalaria, Cotylea and Mesogyne are palinactinodromous; species from sections Saxifraga, Ciliatae, Bronchiales and Trachyphyllum, in which some have lobed and some have entire leaves, are either palinactinodromous or acrodromous, according to the leaf margin; species from sections Ligulatae and Porphyrion, whose hydathodes secrete calcium bicarbonate, have camptodromous venation. Intermediate states occur in section Gymnopera (between palinactinodromous and camptodromous) and in section Porphyrion subsection Oppositifoliae and section Xanthizoon (intermediate between acrodromous and camptodromous). The pattern of distribution across the genus and selected outgroups shows that the ancestral state is likely to be palinactinodromous.

New plant fossils from the Lower Cretaceous of the Parnaíba Basin, Northeastern Brazil: Southern Laurasia links

“…On the other hand, it shows ancestral features (like low-order veins, which are less organized or asymmetrically distributed along the leaf ) that are also found worldwide. They were distributed in the Early Cretaceous Magnollids and in the first Eudicots (Feild et al 2011, Sack & Scoffoni 2013, Zhang et al 2015. Other components of Codó and Potomac floras also exhibit low vein densities with values in the same range as in distinct non-angiosperm clades, supporting the idea that this were probably an ancestral feature of angiosperms, like proposed by Feild et al (2011).…”

Leaf venation patterns in Saxifraga L. species (Saxifragaceae) of Indian Western Himalaya and its taxonomic implications

“…In this species young leaves showed acrodromous (perfect-basal) type of venation but the mature leaves showed palinactinodromous venation. This species and other species of this section are reported to have palinactinodromous venation (Zhang et al, 2015).…”

“…One species of this section S. pseudopallida (now Micranthes melanocentra was studied in the present work and palinactinodromous venation was recorded in it. This section is known to have palinactinodromous venation as reported by Zhang et al (2015).…”

“…The types of venations in studied 30 species are listed in Table 1 and compared with the earlier report by Zhang et al (2015). The illustrations of the types of leaf venation patterns are drawn in Figure 1.…”

“…Fuller and Hickey (2005) studied venation of 2 species of Saxifraga as out group while making their studies in Gunneraceae. Zhang et al (2015) have reported leaf venation patterns in 150 species of Saxifraga including many Sino-Himalayan species and representing 13 sections of the genus. Three main types of venation patterns in the genus were reported as -acrodomous, camptodromous and palinactinodromous.…”