Original URL: http://www.inform.umd.edu/PBIO/pb250/gymn.html

PBIO 250 Lecture Notes

James L. Reveal

Norton-Brown Herbarium, University of Maryland


Selected Families of Gymnosperms

General botany review from PBIO 100
Excellent summary from Ohio State
Gymnosperm section from Encyclopaedia Britannica
Overall review from Texas A&M
Summary of the classification of the gymnosperms according to Reveal; for more details see this full summation
Gymnosperm reproduction
Images of select Pinales from Australia
Images of the major groups within the division; start at the beginning to learn more about dendrology
University of Delaware Botanical Garden has horticultural information and illustrations of many of the common conifers
"seed ferns" or progymnosperms [REQUIRED READING]

Other names at the rank of division
cycads (Cycadophyta Bessey, 1907)
ginkgos (Ginkgoophyta Bold ex Reveal, 1996)
conifers (Pinophyta Cronquist, Takht. & Zimmerm. ex Reveal, 1996)
gnetophytes (Gnetophyta Bessey, 1907)
  1. Burns, R.M. & B.H. Honkala. 1990. Silvics of North America. 1. Conifers. U.S.D.A. Handb. 654.
  2. Hart, J.A. 1987. A cladistic analysis of conifers: Preliminary results. J. Arnold Arbor. 68: 269-307.
  3. Jones, D.L. 1993. Cycads of the world. Washington, D.C.
  4. Kramer, K.U. & P.S. Green. 1990. Pteridophytes and gymnosperms. Vol. 1. In: K. Kubitzki (ed.), The families and genera of vascular plants. Berlin.
  5. Krüssmann, G. 1972. Handbuch der Nadelgehölze. Berlin.
  6. Little, E.L., Jr. 1979. Checklist of United States trees (Native and naturalized). Agric. Handb. 541.
  7. Silba, J. 1986. Encyclopaedia coniferae. Phytologia Mem. 8: 1-127. Pinophyta Cronquist, Takht. & Zimmerm. ex Reveal, 1996
      Cycadophytina Cronquist, Takht. & Zimmerm., 1966
        Cycadopsida Brongn., 1843
          Cycadidae Reveal, 1996
            Cycadales Dumort., 1829
    Cycadaceae Pers., 1807: Dioecious palm-like trees to 15 m with trunks clothed in persistent lf-based; lvs large, circinate; sporophylls spirally arranged in definite male cones and leafy, often toothed females ones; seeds naked, terminal. 1 genus, 20 species. Mostly southern hemisphere; Africa to Japan and Australia. Go to Cardillo & Samuels to review the morphology of Cycadophytina.

    Zamiaceae Horan., 1834: Dioecious, thick and shorted-stems trees to 18 m often with underground stems; lvs large, pinnate; sporophylls in determinate cones with the scales of the female ones peltate and 2(3) ovules on the adaxial margin; seeds naked. 9 genera, 85 species. Warm regions; Africa, Australia, America. The family Boweniaceae D.W. Stevenson (Amer. J. Bot. 68: 1104-1114. 1981), based on Bowenia (2 sp., Australia), with decompound leaves, circinate ptyxis, and cones on short determinate branches, is regarded here as a synonymy of Zamiaceae. The family Stangeriaceae L.A.S. Johnson with midrib and lateral nerves rather than numerous parallel or wavy, simple or forked nerves (as in Zamiaceae, s.s.) is recognized by many: it includes only the genus Stangeria (1 sp., Australia). To read more about cycads, see the site at Museum of Paleontology at Berkeley and follow the links. Information about Encephalartos with good photographs may be found here

      Ginkgophytina Cronquist, Takht. & Zimmerm. ex Reveal, 1996
        Ginkgoopsida Engl., 1898
          Ginkgoidae Reveal, 1996
            Ginkgoales Bessey, 1910
    Ginkgoaceae Engl., 1897: Erect deciduous trees with fan-shaped lvs with open dichotomous venation on long and short shoots; microsporangiophores borne on catkin-like axis with spores released as pollen and each containing two, large multicilitated sperms; megasporangiophores borne on a peduncle in the axil of the lvs, the ovules 2(4) per peduncle, fleshy, often malodorous; cotyledons 2. 1 genus, 1 species. Known only from cultivation, originally from China. Read about the history and uses of Ginkgo biloba; ginkgo is now a popular medicinal plant. Go to Cardillo & Samuels to review the morphology of Ginkgoophytina.

      Pinophytina Cronquist, Takht. & Zimmerm. ex Reveal, 1996
        Pinopsida Burnett, 1835
          Pinidae Cronquist, Takht. & Zimmerm., 1966
            Pinales Dumort., 1829
    Go to Cardillo & Samuels to review the morphology and life cycle of Pinophytina - see images of all the families
    Pinaceae Lindl., 1836: Short to tall, typically evergreen, resinous, monoecious trees with opposite or whorl branches; lvs linear and often needle-like, spirally arranged; male cones small, herbaceous; female cones usually woody with spirally arranged scales bearing 2 seeds per scale; seeds often winged; cotyledons several. 10 genera, 194 species. Mainly north temperate regions to Malesia and Central America. Note: Ongoing work on this family will likely result in it being restricted to Pinus with the remaining genera placed in Abietaceae Bercht. & J. Presl, nom. cons., 1820. Summary from the University of Wisconsin. Go to Cardillo & Samuels to review the morphology of Pinaceae. The site on bristlecone pine tells of these 4000 year old and more conifers.

            Cupressales Bromhead, 1838
    Cupressaceae Rich. ex Bartl., 1830: Low and spreading shrubs to small trees or tall and often massive trees, evergreen, monoecious or dioecious; lvs decussate or in whorls, often needle-like in juvenile vegetation or spirally arranged, linear or needle-like; cones small, solitary, axillary or terminal on short shoots, woody, leathery or berry-like, the cone-scales opposite or in whorls of 3s, the ovules usually several per scale or with spirally arranged bracts and scales; cotyledons usually 2. 28 genera, 129 species. Cosmopolitan. Ample evidence now points to a reduction of Taxodiaceae to synonymy under Cupressaceae. Go to Cardillo & Samuels to review the morphology of Taxodiaceae and Cupressaceae. Many members of conifers are markedly different in the Southern Hemisphere, such as Callitris (Cupressaceae), Agathis (Araucariaceae - look at these "needles"!), and Podocarpus (Podocarpaceae). See summary of Araucariaceae, Podocarpaceae, and Cephalotaxaceae

          Taxidae Ehrend. ex Reveal, 1996
            Taxales Knobl., 1890
    Taxaceae Gray, 1821: Low and spreading shrubs to small trees, evergreen, monoecious or dioecious; lvs linear, needle-like, spirally arranged; microsporangiophores small cones, scale-like or peltate with 2-8 pollen-sacs; megasporangiophores fleshy "cones" with decussate bracts and a single ovule, arillate; cotyledons 2. 5 genera, 17 species. Northern hemisphere south to Malesia and New Caledonia. See summary of Taxaceae from the University of Wisconsin. Go to Cardillo & Samuels to review the morphology of Taxaceae.

      Gnetophytina Cronquist, Takht. & Zimmerm. ex Reveal, 1996
        Ephedropsida L. Benson ex Reveal, 1996
          Ephedridae Cronquist, Takht. & Zimmerm. ex Reveal, 1996
            Ephedrales Dumort., 1829
    Go to Cardillo & Samuels to review the morphology of Gnetaceae and Welwitschiaceae.
    Ephedraceae Dumort., 1829: Xeromorphic shrubs, mostly dioecious; lvs opposite or in whorls of 3-4 scale-like non-photosynthetic segments; branches slender, green and photosynthetic, often grooved; female inflorescences a short shoot with 2-4 pairs or whorls of bracts and 1-3 megasporangiophores; male inflorescences subtended by a bract with a single, central, usually forked microsporangiophore; cotyledons 2. 1 genus, 40 species. Arid regions of Eurasia and the New World. The remaining two families, Welwitschiaceae (1 sp., sw Africa on the Namib Desert) and Gnetaceae (30 sp., tropical South America, Africa, southeastern Asia and Indonesia), each belonging to their own class, Gnetopsida Engl. (1898) and Welwitschiopsida B. Boivin (1956). The drug ephedrine comes from members of this genus. See pictures of Ephedra torreyana from the Spring Mountains of Nevada with close-ups of the male and female strobuli. Go to Cardillo & Samuels to review the morphology of Ephredaceae.

Other Sites of Interest:
Conifers of the Pacific Northwest from Oregon State University
Conifer characteristics - slow to load

Next Series of Lecture Notes:
Magnoliidae
Lecture Schedule
Last revised: 22 Jan 1999