angiosperm

A flowering vascular plant that produces seeds within mature ovaries
(fruits). The angiosperms form a single lineage.

antheridium

(plural: antheridia) The sperm- producing structure in most land
plants except angiosperms.

archegonium

(plural: archegonia) The egg-producing structure in most land plants
except angiosperms.

deciduous

Describing a plant that sheds leaves or other structures at regular
intervals (e.g., each autumn).

dicot

Any flowering plant (angiosperm) that has two cotyledons (embryonic
leaves) upon germination. The dicots do not form a monophyletic group.
Also called dicotyledonous plant. Compare with eudicot and monocot.

endosperm

A triploid (3n) tissue in the seed of a flowering plant (angiosperm)
that serves as food for the plant embryo. Functionally analogous to
the yolk in some animal eggs.

eudicot

A member of a monophyletic group (lineage) of angiosperms that
includes complex flowering plants and trees (e.g., roses, daisies,
maples). All eudicots have two cotyledons, but not all dicots are
members of this lineage. Compare with dicot and monocot.

gametangium

(plural: gametangia) (1) The gamete-forming structure found in all
land plants except angiosperms. Contains a sperm-producing antheridium
and an egg-producing archegonium. (2) The gamete-forming structure of
some chytrid fungi.

gymnosperm

A vascular plant that makes seeds but does not produce flowers. The
gymnosperms include five lineages of green plants (cycads, ginkgoes,
conifers, redwoods, and gnetophytes). Compare with angiosperm.

heterospory

(adjective: heterosporous) In seed plants, the production of two
distinct types of spores: microspores, which become the male
gametophyte, and megaspores, which become the female gametophyte.
Compare with homospory.

homospory

(adjective: homosporous) In seedless vascular plants, the production
of just one type of spore.

megasporangium

(plural: megasporangia) In heterosporous species of plants, a
spore-producing structure that produces megaspores, which go on to
develop into female gametophytes.

microspore

In seed plants, a haploid (n) spore that is produced in a
microsporangium by meiosis of a diploid (2n) microsporocyte; develops
into a male gametophyte. Compare with megaspore.

monocot

Any flowering plant (angiosperm) that has a single cotyledon
(embryonic leaf) upon germination. Monocots form a monophyletic group.
Also called a monocotyledonous plant. Compare with dicot.