Gymnosperm means naked seed. In some older taxonomic schemes, there is a Class, Gymnospermae, which includes all the seed bearing plants that do not have flowers. The largest group of gymnosperms is the cone bearing plants, the conifers. Our text ranks the conifers as the Division Coniferophyta. Most people are thinking of conifers when they use the term gymnosperms; they seldom know about the Cycadophyta, Ginkophyta, and the Gnetophyta. We will see examples of these divisions in the greenhouse.

Tools: none

Conifers

The conifers comprise an ancient line of seed-bearing plants with extensive secondary growth. Most, but not all, retain their leaves for more than one growing season, hence the term evergreens as a common misnomer for the conifers. Most, but not all, produce seeds on woody strobili called cones.

The genus, Pinus, is a major, Northern Hemisphere conifer. The pine sporophyte is characterized by a xylem dominated by tracheids having bordered pits, a large number of resin canals throughout the plant, a simple microstrobilus, a compound megastrobilus, and leaves in bundles borne on determinant short shoots.

The life history of some pines takes three years from pollination to seed drop. Many reproductive structures were named before the life history was fully elucidated, therefore we have a large number of synonyms to consider. Know each structure by all its names.
 

	Morphological		Traditional		Other
	microstrobilus		pollen cone/male cone
	microsporophyll		bract
	microsporangium		pollen sac
	microsporocyte		microspore mother cell		m.m.c.
	microspore
	microgametophyte		pollen grain,
			prothallial cells
			tube cell
			generative cell
	microgametes		sperm cells
	megastrobilus		ovulate cone		female cone,
			ovuliferous scale		seed scale complex
			ovule
	megasporangium		nucellus
			integuement		seed coat
	megasporocyte		megaspore mother cell		M.M.C.
	megaspore
	megagametophyte		female gametophyte
	megagametangium		archegonium
	megagamete		egg
			embryo

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