PLANT FOSSILS, VASCULAR CRYPTOGAMS
LEPIDODENDRON & RELATIVES
1.a. Examine the surface of a Lepidodendron stem. Describe the appearance and pattern of leaf scars and leaf bases.
1.b. Now look at a coal ball peel cross section of a Lepidodendron stem. Do you see evidence of a vascular cambium? How old was your stem?
1.c. Find Stigmaria (the organ-genus for Lepidodendron roots). Sketch a root with rootlet scars. The fossil on demonstration shows the boundary of the stele (the endodermis). How does this fossil suggest that the function of the Lepidodendron root was storage?
1.d. Compare the large root section with the coal ball peels of rootlets. 1.e. Find fossils (impressions and coal ball peels) of Lepidodendron (Lepidophylloides) leaves. Sketch the leaf and its leaf base in the space below. Assume the scale that 1cm = 10cm for you drawing.
1.f. Now look at the lycopod strobilus fossils. Sketch one into the space below. Label: sporophyll, microsporangium, megasporangium, and cone axis. CALAMITES & RELATIVES
2.a. Describe a Calamites stem from fossils on demonstration. How does this structure resemble the stems of Equisetum?
2.b. Now investigate coal ball peel sections of Calamite stems (Arthropitys). In what ways do the stem still resemble those of Equisetum? In what important way do the Calamite stems differ from those of Equisetum?
2.c. Astromyelon is the organ-genus for Calamite roots. How do they differ from the Calamite stems?
2.d. Annularia is the organ-genus associated with the leafy branches of Calamites. How do they resemble the leaves of Equsetum and Sphenophyllum? FERNS
3.a. Locate fossils of a variety of ferns. The primary organs represented include stems, petioles, and leaf sections. Identify the stem sections, particularly those of Psaronius, and locate the stele. What is the stele type?
3.b. Look for tissues in the leaf and petiole sections. What group of ferns do these fossil forms most closely resemble?
4. Examine Zygopteris stem sections. What is the stele type? Make a topographic sketch of a stem in the space below. ARCHAEOPTERIS
5.a. Find fossils of Archaeopteris leafy branches. Study the leaves and add them to the branch system below.
5.b. What is the fundamental difference between this structure and the megaphylls of a fern?
5.c. How do the individual leaves resemble those of Ginkgo?