BIOL 1020 Lecture Notes - Cork Cambium, Vascular Cambium, Xylem
Document Summary
Gymnosperm evolution: seed plants, extant clades of seed plants. Gymnosperms (naked seed: the seeds are exposed on sporophylls that form cones (strobili): numerical dominance, biomass, geographical expanse= dominate. 35. 19: anything beyond phloem is considered as bark. Bark has the cork cambium: dendrochronology: growth rings, higher indices represent bigger rings, and greater temperature. Diversity of gymnosperms: four extant phyla, cycadophyta (cyads) Thrived during the mesozoic, but relatively few species exist today. Species vary in appearance, and some are tropical whereas others live in deserts. Welwitschia: only one species, desert plant, sw africa. Leaves among the largest of all plants: ovulate cones. 40 species: arid regions, global, ephedrine, gnetophyta. It has a high tolerance to air pollution and is a popular ornamental tree: coniferophyta (conifers, pine, fire, redwood) Most conifers are evergreens and can carry out photosynthesis year round. Douglas fir: main timber species in north america. Deciduous conifer (looses its pines during the winter)
