School of Sciences, Lautoka Campus BIO509 Botany Lecture 17: Other Phyla of Gymnosperms

Phylum Ginkgophyta There is only one living species if Gingko (from the Chinese word meaning silver apricot). They have characteristic notched, broad fan-shaped leaves which look like larger versions of the maidenhair ferns. Leaves have no midrib or prominent veins. Hair like veins branch dichotomously.

Gingko is dioecious – has male and female reproductive organs on different individual plants. Mature seeds look like small plums, and are enclosed in fleshy seed coats. The flesh is unrelated to true fruits. Life cycle similar to pines.

Ginkos are probably extinct in the wild, but has been preserved in temple grounds and parks in China and Japan. In North America male plants are preferred because the seed flesh (females) has a nauseating odour and is irritating to the skin. In China and Korea, the seeds are considered a delicacy, and only enough male plants are kept for ensure pollination.

The largest Gingko tree in the world is estimated to be around 1,200 years old. This tree lives at the Hida-Kokobunji Temple in Takayama, Japan. Image - Wikimedia commons

Phylum Cycadophyta – the Cycads Appearance of a cross between a tree fern and a palm.

Slow-growing plants of the tropics. Un-branched trunks which can grow more than 15m tall Crown of largely pinnately divided leaves. Life Cycle similar to conifers but cycads have flagellated sperms. Pollination is generally brought about by beetles instead of wind. Many are facing extinction.

Cycads are dioecious. Most species have pollen and seed cones on separate plants. Some species have pollen cones but lack ovulate cones and have instead reduced leaves with ovules attached.

Phylum Gnetophyta There are about 70 species (three distinct genera- Gnetum, Welwitschia and Ephedra). They are unique among gymnosperms in that they have vessels in the xylem Ephedra Gnetum Welwitschia

Genus Ephedra Mostly shrubby plants. Found in the drier regions Small leaves produced in twos or threes. Stems and branched are slightly ribbed and photosynthetic

Genus Gnetum (most common) Occurs in the tropics Most are vine-like. Broad leaves – similar to flowering plants. Leaves opposite, leathery, dicot-like Produce flower- & seed-like structure

Genus Welwitschia Stems are only a small distance from the ground in the form of a large shallow cup that tapers at the base into a long taproot. Only produce two leaves throughout their life span. Leaves are long but because they are close to the ground they get damaged easily. Only produce two leaves throughout their life span. Plants live very long (100 years).

Plants are dioecious.

Human and ecological relevance of Gymnosperms. This group is second only to angiosperms in importance to the world and to humans. Ecological importance—dominant tree in boreal and temperate montane forests. Conifers dominate large areas of natural vegetation in the world (much of it “boreal forest”), particularly in N. Europe, Asia, and N. America, and in mountains elsewhere in temperate areas

Economic importance of conifers Timber—for all kinds of uses Paper—as pulpwood for making paper Food—various parts are edible Chemicals—from the bark, resin, etc.

Economically important pine species in Pacific. Agathis Agathis macrophylla (Pacific kauri, dakua makadre) most important native timber tree. Agathis australis (NZ kauri) - largest tree in the Pacific?

Pinus carribea Most important timber species in Fiji

Conifers for Food. Bark eaten in North America. Needles for antiscurvy tea in North America. Pine nuts were and still are harvested and sold, and sometimes sold, for food in many parts of the world.

Chemicals from Conifers Turpentine used as a paint solvent. Rosin for waxing musical instruments. Pitch or patching canoes and nowadays for chemicals. Tannin for tanning leather. Medicines, e.g., Taxol used for treating breast cancer. Aromatic compounds, such as incense cedar. Resins, such as Canadian balsam, used as adhesives. Amber (fossilized conifer resins). Juniper berries used flavoring gin.

Questions??