gymnosperm A group of flowerless plants that
includes pines, conifers, redwoods, firs, yews, and
cycads. Gymnospermmeans “naked seed.” Their ovules
and the seeds, which develop in them, are born unpro-
tected on the surface of megasporophylls, and are often
arranged on cones instead of being enclosed in ovaries
as in the flowering plants. They release pollen directly
into the air, which finds its way to female ovules and
fertilizes them. The earliest examples of gymnosperms
appeared during the Devonian period some 408 million
years ago and were seed ferns. Gymnosperms have
reached as high as 350 feet to as small as 4 inches in
height. Worldwide there are 20 plant families with at
least 50 percent of their species threatened. Of these,
eight are gymnosperm families (including cycads and
conifers). This may be due to the fact that many of their
species are widely exploited for both timber and horti-
cultural purposes, and, because they are an ancient
group, they may not adapt easily to the rapidly chang-
ing environment around them. There are only 720
species compared with 250,000 species of angiosperms.
See alsoANGIOSPERM.gynandromorphism Afemale that develops partly
or completely male characteristics. A lateral gynandro-
morph on one side has the external characters of the
male, and the other side has those of the female. Com-
mon in bees and silkworms.
See alsoHERMAPHRODITE.154 gymnosperm