CONIFERS AND GYMNOSPERMS
Within the plant kingdom there are two major groups of seed-producing plants, angiosperms and gymnosperms. Angiosperms are flowering plants; the seed is usually produced in an ovary (fruit) which develops in the flower. Gymnosperms are usually trees or shrubs in which the ovules or seeds are naked, growing on the scales of cones or conelike structures (not enclosed in an ovary). Cycads are the most primitive extant gymnosperms.
Conifers are the largest subgroup of gymnosperms, and are further divided into the pine family (Pinaceae); cypress family (Cupressaceae), which includes redwood and sequoia (formerly included in Taxodiaceae); and yew family (Taxaceae).
Conifers are plants which produce a naked seed rather than a seed encased in fruit; pollen is always borne in cones or similar structures. Conifers usually, but not always, have needle- or scale-like leaves, and are usually, but not always, evergreen, rather than deciduous. Some are shrubs, but most are trees.
The pine family includes pines, firs, spruces, hemlocks, larches, and Douglas-firs. The cypress family includes junipers, incense cedar, redcedar, cypresses and false-cypresses.
The 7 families of conifers (per Gymnosperm Database) are:
Pinaceae – the pine family, largest family of conifers with around 250 species.
Auricariaceae – an ancient family, once diverse and throughout the globe but now only three genera are found and are limited the southern hemisphere.
Podocarpaceae – large family found mostly in the southern hemisphere with approximately 156 species.
Sciadopityaceae – only one species found in Japan, Sciadopitys verticellata.
Cupressaceae – the cypress family, around 140 species which includes junipers and redwoods.
Cephalotaxaceae – small family of around 20 species, often clumped together with Taxaceae.
Taxaceae – the yew family with around 30 species.
This site includes conifers native to California, and also includes many exotic conifers that are cultivated and thrive in the Mediterranean-type climate of the San Francisco Bay Area, plus a few I found in local botanic gardens and couldn't resist. Descriptions are based on field observations, coursework, and reading. References here.