Flashcards in Gymnosperms Deck (21)
What are Gymnosperms?
Vascular 'naked' seed plants
What is a key characteristic of gymnosperms?
Seeds usually exposed on. modified leaves called strobili
When did the gymnosperms emerge?
In the the Carboniferous, 360MYA
What are progymnosperms?
Transitional species that produce wood and heterospores but are seedless
How are seedless plants represented in the phylogenetic tree?
Two monophyletic sister clades
When did Gymnosperms become the dominant vegetation?
In the Permian when climate dried out, and remained throughout the mesozoic
What are the extinct phyla?
Pteridosperms, Cordaites, Glossopterids
What are the extant phyla?
Cycads, Ginkgophyta, Gnetoyphyta, Coniferophyta
what are the characteristics of Pteridosperms?
Extict, evolved from pro gymnosperms, most primitive seed plant,
What are the characteristics of Cordaites?
Extinct, arborescent plants, large, spirally arranged leaves confined to the upper branches
What are the characteristics of Glossopterids?
Trees, made of gymnosperms would, feathery leaves
What are the characteristics of Cycads?
Extant, 160 species, large cones and palmate leaves, massive taproot, dioecious. Slow growing leaves die and become the trunk structure
What is monoecious?
having both the male and female reproductive organs in the same individua
What is dioecious?
having the male and female reproductive organs in separate individuals.
What are the characteristics of Ginkgophyta?
Ginkgobiloba is the only surviving species,- also known as maidenhair tree. Dioecios, female plants smell bad when decaying, planted in cities. Is a living fossil
What are the characteristics of Gnetophyta?
Consists of three genera, species live tropically or in deserts, grouped on molecular data
What are the three genera of Gnetophyta?
Welwitchia, Ephedra, Gnetum
What are the characteristics of Welwitchia?
one species, in the deserts of sw Africa, among some of the largest leaves known
What are the characteristics of Gnetum?
35 species, tropical shrubs and vines, leaves look similar to flowering plants
What are the characteristics of Ephedra?
40 species, worldwide,