gymnosperms

Gymnosperms

Seed plants that produce seeds not enclosed in a fruit; seeds are exposed on sporophylls or cone scales.

Pteridosperms

Extinct seed ferns; early seed plants reclassified as gymnosperms.

Nucellus

Tissue inside the ovule that provides nutrition to the developing embryo.

Integument

Protective layer surrounding the nucellus; becomes the seed coat after fertilization.

Micropyle

Small opening in the integument where pollen enters for fertilization.

Phylum Pinophyta

The phylum that includes conifers such as pines, firs, spruces, and cedars.

Fascicle

Cluster of two to five pine needles that form a short shoot with restricted growth.

Resin canals

Structures that secrete resin; deter insects and prevent fungal growth.

Hardwood

Broadleaf tree wood containing thick-walled vessels and fibers.

Megasporocyte

Diploid cell that undergoes meiosis to form four megaspores; one survives.

Archegonium

Female organ that produces eggs.

Pollen tube

Carries sperm to archegonium for fertilization.

Pine Reproduction Timing

Takes two years for seed cones to mature, involving pollen tube growth and fertilization.

Zygote

The fusion of sperm and egg that develops into an embryo.

Seed Coat

The protective outer layer formed from the integument.

Aril

A fleshy cuplike covering around ovules found in yew and nutmeg trees.

Taxol

A cancer drug sourced from the single ovules with fleshy aril produced by Yew (Taxus).

Podocarpus

A southern hemisphere conifer known for fleshy-coated seeds and a large appendage at the base.

Dioecious

A reproductive strategy where male and female trees are separate, as seen in Ginkgo.

Ginkgo biloba

The sole living species in Phylum Ginkgophyta, known as the maidenhair tree.

Ginkgo Leaves

Broad, fan-shaped, and dichotomously veined leaves characteristic of Ginkgo.

Cycads

Slow-growing tropical gymnosperms with unbranched trunks and pinnate leaves, dioecious in reproduction.

Gnetophyta

A phylum of gymnosperms with vessels in xylem, including Ephedra, Gnetum, and Welwitschia.

Ephedra

Shrubby desert plants that produce male and female strobili.

Gnetum

Tropical vine-like plants characterized by broad leaves.

Welwitschia

A desert plant with a short stem, long taproot, and two straplike leaves; dioecious.

Human uses for conifers

Furniture, paper, resin (turpentine and rosin), food, fuel, and ornamentals.

Human use for ginkgo

Edible seeds and extracts that improve blood circulation.

Human uses for ephedra

Source of ephedrine, which is used in respiratory medicines.