The Elements of Botany, For Beginners and For SchoolsGray, Asa
Science
The Elements of Botany, For Beginners and For Schools
Gray, Asa
Plants
314. While the ordinary simple pistil is conceived by the botanist to be
a leaf rolled together into a closed pod (306), those of the Pine, Larch
(Fig. 337), Cedar, and Arbor-Vitæ (Fig. 338, 339) are open leaves, in
the form of scales, each bearing two or more ovules on the inner face,
next the base. At the time of blossoming, these pistil-leaves of the
young cone diverge, and the pollen, so abundantly shed from the
staminate blossoms, falls directly upon the exposed ovules. Afterward
the scales close over each other until the seeds are ripe. Then they
separate that the seeds may be shed. As the pollen acts directly on the
ovules, such pistil (or organ acting as pistil) has no stigma.
315. In the Yew, and in Torreya and Gingko, the gynœcium is reduced
to extremest simplicity, that is, to a naked ovule, without any visible
carpel.
316. In Cycas the large naked ovules are borne on the margins or lobes
of an obvious open leaf. All GYMNOSPERMOUS plants have other
peculiarities, also distinguishing them, as a class, from ANGIOSPERMOUS
plants.
Section XI. OVULES.
317. =Ovule= (from the Latin, meaning a little egg) is the technical
name of that which in the flower answers to and becomes the seed.
[Illustration: Fig. 340. A cluster of ovules, pendulous on their
funicles.]
318. Ovules are _naked_ in gymnospermous plants (as just described), in
all others they are enclosed in the ovary. They may be produced along
the whole length of the cell or cells of the ovary, and then they are
apt to be numerous, or only from some part of it, generally the top or
the bottom. In this case they are usually few or single (_solitary_, as
in Fig. 341-343). They may be _sessile_, i. e. without stalk, or they
may be attached by a distinct stalk, the FUNICLE or FUNICULUS (Fig.
340).
[Illustration: Fig. 341. Section of the ovary of a Buttercup,
lengthwise, showing its ascending ovule.]
[Illustration: Fig. 342. Section of the ovary of Buckwheat, showing the
erect ovule.]
[Illustration: Fig. 343. Section of the ovary of Anemone, showing its
suspended ovule.]
319. Considered as to then position and direction in the ovary, they are
_Horizontal_, when they are neither turned upward nor downward, as in
Podophyllum (Fig. 326),
_Ascending_, when rising obliquely upwards, usually from the side of the
cell, not from its very base, as in the Buttercup (Fig. 341), and the
Purslane (Fig. 272),
_Erect_, when rising upright from the very base of the cell, as in the
Buckwheat (Fig. 342),
_Pendulous_, when hanging from the side or from near the top, as in the
Flax (Fig. 270), and
_Suspended_, when hanging perpendicularly from the very summit of the
cell, as in the Anemone (Fig. 343). All these terms equally apply to
seeds.
320. In structure an ovule is a pulpy mass of tissue, usually with one
or two coats or coverings. The following parts are to be noted, viz.--
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