Summarizing Early Plant Life

Summary

Land plants acquired traits that made it possible to colonize land and survive out of the water. All land plants share the following characteristics: alternation of generations, with the haploid plant called a gametophyte, and the diploid plant called a sporophyte; protection of the embryo, formation of haploid spores in a sporangium, formation of gametes in a gametangium, and an apical meristem. Vascular tissues, roots, leaves, cuticle cover, and a tough outer layer that protects the spores contributed to the adaptation of plants to dry land. Land plants appeared about 500 million years ago in the Ordovician period.

Glossary

antheridium

male gametangium

archegonium

female gametangium

charophyte

other term for green algae; considered the closest relative of land plants

diplontic

diploid stage is the dominant stage

embryophyte

other name for land plant; embryo is protected and nourished by the sporophyte

extant

still-living species

extinct

no longer existing species

gametangium

structure on the gametophyte in which gametes are produced

haplodiplodontic

haploid and diploid stages alternate

haplontic

haploid stage is the dominant stage

heterosporous

produces two types of spores

homosporous

produces one type of spore

megaspore

female spore

microspore

male spore

non-vascular plant

plant that lacks vascular tissue, which is formed of specialized cells for the transport of water and nutrients

seedless vascular plant

plant that does not produce seeds

sporocyte

diploid cell that produces spores by meiosis

sporopollenin

tough polymer surrounding the spore

vascular plant

plant containing a network of cells that conducts water and solutes through the organism