Vascular Non-Flowering Seed Plants
- Conifers are vascular nonflowering seed plants.Anna Yu/Photodisc/Getty Images
The majority of all terrestrial plant species are vascular. Vascular plants are those that have an extensive vascular system, comprising of xylem vessels and phloem cells. Xylem vessels transport minerals and water while phloem cells transport sugars throughout the plant. Vascular plants are subdivided into nonflowering, or gymnosperms, and flowering plants, called angiosperms. Vascular nonflowering seed plants are also called seed-producing gymnosperms. - Conifers are a large group of vascular nonflowering seed plants belonging to the Pinaceae family. Conifers produce characteristic needle-like foliage and most bear naked seeds arranged in the form of cones. Most members are evergreen, but some, including the bald cypress and the larch, shed their foliage each fall to grow new needles in the spring. Conifers are among some of the most diverse plant species and appear extensively in both the Northern and Southern hemispheres. Junipers, spruce, cedar, cypress, hemlock, arborvitae and English yew are examples of conifers.
- Ginkgoales or Ginkgoaceae is a family of vascular nonflowering seed plants that, as of October 2010, consists of only the species Ginkgo biloba. Ginkgo biloba, also called ginkgo, is one of the only species of living trees without any close relatives. It is a large tree, reaching heights greater than 70 feet. Ginkgo is resistant to snow, wind, disease and insects, and its long, aerial roots makes it long lived. Ginkgo biloba is pollution tolerant and is popularly cultivated as a street tree in many parts of China. According to Karl J. Niklas in the book "The Evolutionary Biology of Plants," the Ginkgo biloba tree is considered a "living fossil" due to its status as the single extant member of the Ginkgoaceae family.
- Gnetales is a class of plant represented by three genera, namely Welwitschia, Gnetum and Ephedra that together encompass approximately 67 species. Members are diverse in physical appearance and occur as both shrubs and trees. Gnetales, according to Hsüan Keng, Ro-Siu Ling Keng in the book "Orders and Families of Malayan Seed Plants," are the most specialized of the gymnosperms, owing to their specialized vascular systems. Most species are climbing plants with twining stems. Welwitschia mirabilis is a unique, endangered member of the Gentales class of plants, which has a single pair of large, fibrous and wide leaves that it retains throughout its life. The plant is found in hot deserts and is known to survive more than a 1,000 years on less than an inch of water annually, according to Shar Levine and Leslie Johnstone in the book "Plants: Flowering Plants, Ferns, Mosses and Other Plants."
