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A pseudo-reticulate venation that is actually a highly modified penniparallel one is an autapomorphy of some Melanthiaceae, which are monocots; e.g., Paris quadrifolia (True-lover's Knot). In leaves with reticulate venation, veins form a scaffolding matrix imparting mechanical rigidity to leaves. [34]
Reticulate evolution can happen between lineages separated only for a short time, for example through hybrid speciation in a species complex. Nevertheless, it also takes place over larger evolutionary distances, as exemplified by the presence of organelles of bacterial origin in eukaryotic cells.
Reticulate venation seems to have appeared at least 26 times in monocots, and fleshy fruits have appeared 21 times (sometimes lost later); the two characteristics, though different, showed strong signs of a tendency to be good or bad in tandem, a phenomenon described as "concerted convergence" ("coordinated convergence"). [133] [134]
Glossopteris should strictly be used to refer to the distinctive spathulate fossil leaves with reticulate venation, however, the term has also been used to refer to the parent plant as a whole. [37] Leaves of Glossopteris are associated with reproductive structures belonging to the family Dictyopteridiaceae within the Glossopteridales.
The leaves are in pairs or whorls of three, thick and leathery, dark-green, narrow lanceolate, 5–21 centimetres (2–8 inches) long and 1–3.5 cm (3 ⁄ 8 – 1 + 3 ⁄ 8 in) broad, and with an entire margin filled with minute reticulate venation web typical of eudicots. The leaves are light green and very glossy when young, maturing to a ...
Members of this family can be herbaceous to "woody" vines. They grow from their rhizomes and are often armed with prickles on the stems and/or leaves. Leaves are alternate and simple; and entire to spinose-serrate. Some members of this family have coriaceous (leathery) leaves. Venation of the leaves may be palmate to reticulate.
[7] [8] [9] The abaxial leaf surface posesses prominent, reticulate venation. [2] In Victoria amazonica the leaves are glaberous, with long, hard spines and the underside is red. In Victoria cruziana the leaves are fuzzy with soft spines and the underside is purple. The shape of the rims is also different. [10]