Modified from Dr. Sue Hartley’s BTNY1203 Plants 3 Modified from Dr. Sue Hartley’s BTNY1203

Divisions of plants Non vascular Vascular Mosses Liverworts Hornworts algae Nonseeded e.g. ferns Seeded i.e. angiosperms and gymnosperms.

Gymnosperms Conifers (Pinophyta or Coniferophyta): the cone bearers; include pine, spruce, fir, redwood, cedar, juniper, yew Cycads (Cycadophyta): cycads, sago palms (not true palms, which are angiosperms) Ginkgo (Ginkgophyta): Ginkgo biloba is only extant species Gnetophytes (Gnetophyta) = only gymnosperms with vessels in the xylem: Ephedra (Mormon tea), Welwitschia mirabilis (only species), and Gnetum

What is a gymnosperm? Gymnosperm: the naked seed. plants that do not enclose their seeds in an ovary. Do gymnosperms produce fruit?

Conifers Conifers are native to places with harsh winters: high elevations and northern latitudes. During the winter, the humidity is very low, and liquid water is scarce. Many conifers are evergreen, so keeping their leaves through winter poses a threat of serious water loss by transpiration. Needle-like and scale-like leaves have a low surface area relative to leaf volume. This decreases transpiration. Various other structure features of the conifer leaves decrease transpiration, including sunken stomata, a thick cuticle layer, a hypodermis, and an endodermis (Figure 7.12). By having xeric-adapted leaves, conifers can enjoy the benefits of being evergreen while minimizing water loss. With a short growing season, evergreens can use any chance to do photosynthesis and other aspects of metabolism. For northern and high latitude conifers, photosynthesis does not stop until air temperatures drop below about 20oF (-6oC), the temperature at which they no longer have liquid cellular water.

Cycads Cycads are dioecious, with male strobili on one plant and female strobili on another.

Ginko Ginkgo biloba is dioecious, with male structures produced on one tree and female on another. Usually when the tree is planted as an ornamental, males are used because the females produce a seed with a fleshy seed coat that has an odor that most people find offensive. The fan-shaped leaves are deciduous.

Gnetophytes Ephedra grows in the southwest deserts of North America. It is dioecious. The upper photo shows a pollen-producing male structure. The two lower photos show female Plant Welwitschia

Angiosperms •reproductive structures in a flower • seed is covered by a fruit formed from the ovary and accessory floral parts • the fruit protects the seed during development and provides a means to disperse the mature seed – monocots – eudicots

Dicots Petals and sepals in sets of four or five Leaf veins not parallel