2. Pinoideæ. The ovules have two integuments, the external one of which is leaf-like and becomes developed as the “ovuliferous scale”; if there are several of these in each flower they unite and form a “symphyllodium.” This may remain free or unite with the bract. The cones are most frequently woody, rarely succulent. The seeds are hidden among the cone-scales.
Family 1. Taxoideæ.
This family, considered to be most nearly related to the Cycadeæ, also made its appearance at a very early period. There is only one order.
Order. Taxaceæ. The characters have been given above.
A. Cephalotaxeæ is the oldest group, presumably the connecting link between the Cycadeæ and the other Coniferæ. The flower consists normally of two ovules. Aril wanting. One integument. Seeds drupaceous.—The flowers in Ginkgo biloba (Salisburia) are situated in the axil of foliage- or scale-leaves. The stamens bear only two pollen-sacs (Fig. [260] A). The female flower has two ovules, placed together at the end of a long, bare axis (Fig. [260] C). Round the base of the ovule a small collar (ar, in Fig. [260] D) is found, which may probably be considered homologous with the collar-like outgrowth which surrounds the base of the Cycas-ovule. The seed resembles a Plum, and has a fleshy external coat, surrounding a hard internal layer. The embryo is developed after the seed has fallen off. The Ginkgo-tree has long-stalked, fan-shaped leaves, more or less indented, with dichotomous veins resembling certain Ferns—the Adiantums. It is a native of East Asia, and the only surviving species of a genus which in earlier times was very rich in species, and distributed over the entire Northern Hemisphere. Cephalotaxus (Eastern Asia) is related to it.
Fig. 260.—Ginkgo (nat. size): A a branch with a small flowering dwarf-branch (male flower); B a leaf; C a flower with two ovules; D a ripe seed; ar collar.
Fig. 261.—Phyllocladus glaucus: a branch with female flowers (nat. size).
B. Podocarpeæ. The female flower is reduced to one ovule, placed in the axil of a bract, or a little forward upon it. The ovule has an aril (2 integuments).—Phyllocladus (Fig. [261]), from New Zealand and Tasmania, has obtained its name from its flat, leaf-like branches, the leaves proper being scale-like (f). The ovules stand erect in the axil of the scale-like leaves (c), and several are collected at the end of short branches.—Microcachrys tetragona (Tasmania) has a small female catkin with several spirally-placed, fleshy bracts, at the end of which the inward and downward turned ovule is attached (Fig. [262] A, A’). The ripe cones are red, succulent, and resemble Strawberries.—In Dacrydium (Tasmania, New Zealand, Malaysia) the female cone has most frequently only 1–2 (–6) bracts, which resemble the vegetative leaves; they have also a fleshy aril (Fig. [262] B, B’).—Podocarpus (40 species, East Asia, S. Temp.); the bracts of the female flowers become fleshy, and unite together; only 1 or 2 are of use in supporting the flowers. The ovules project high above the apex of the bract, and are anatropous, the micropyle being turned downwards (Fig. [262] C, D). An aril commences to develope in the flowering period as an external coating, and later on it becomes fleshy and coloured.