_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.
[Illustration: 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.]
[Illustration: 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.
Public-domain text, read in full here on John Shaqi.
Reviews
Reviews
No reviews yet
Be the first to share your thoughts on this work.
Elsewhere in the archive
Join the Discussion
Join the discussion
Sign in to leave a comment or review.
Sign InorCreate an account