Question

3) Leaves are photosynthetic organs found on the sporophytes of most extant vascular plants. Based on a combination of molecular data and fossil evidence, it appears that leaves have evolved more than once. Using the information in Figure 29.13 (p. 629 of your textbook), explain leaf evolution in the vascular plants by answering the following questions. a. Lycophyta are a clade of vascular plants that have leaves called microphylls. Do microphylls represent a synapomorphy or a homoplasy in the Lycophyta? You must explain your answer. b. Megaphylls are found in Monilophyta, the ferns and fern allies, as well as Seed Plants, the gymnosperms and angiosperms. Do megaphylls represent a synapomorphy or a homoplasy in the Monilophyta and Seed Plants? You must explain your answer. Microphyll leaves Microphylls Unbranched vascular tissue Selaginella kraussiana (Krauss's spikemoss) Megaphyll leaves Megaphylls Branched vascular tissue Hymenophyllum tunbrigense (Tunbridge filmy fern) 2017 novine

Answer 1

A. Synapomorphy of lycophytes indicates the the presence or indicates true leaves, and looks like definite patterns and they are present on stem.

They have evolutionary history but they differ from megaphylls which is also a vascular plant.

Microphylls are small and all other microphylls fossils are not small.

They have single vascular bundle

Leaf gaps are not present in stele in production of leaf traces

Stelar and microphylls vascular are two extant Lycopodium species

B) Megaphylls are present in seed plants and ferns leaves of ferns are homologous. Leaves of Megaphylls are homoplasy the recurrence of similarity in evolution the record fossils evidence and developmental path way indicates it.