nfluence, when the two cells run together into one, as they
nearly do in most species of Pentstemon (Fig. 297), more so in Monarda
(Fig. 300), and completely in the Mallow (Fig. 298) and all the Mallow
family.

293. By suppression in certain cases the anther may be reduced to one
cell or halved. In Globe Amaranth (Fig. 299) there is a single cell
without vestige of any other. Different species of Sage and of the White
Sages of California show various grades of abortion of one of the
anther-cells, along with a singular lengthening of the connective (Fig.
302-305).

294. The splitting open of an anther for the discharge of its pollen is
termed its _Dehiscence_.

[Illustration: Fig. 306. Stamen with the usual dehiscence of anther down
the side of each cell.]

[Illustration: Fig. 307. Stamen of Pyrola; cells opening by a terminal
hole.]

[Illustration: Fig. 308. Stamen of Barberry; cells of anther each
opening by an uplifted valve.]

295. As the figures show, this is commonly by a line along the whole
length of each cell, either lateral or, when the anthers are extrorse,
often along the outer face, and when introrse, along the inner face of
each cell. Sometimes the opening is only by a chink, hole, or pore at
the top, as in the Azalea, Pyrola (Fig. 307), etc.; sometimes a part of
the face separates as a sort of trap-door (or valve), hinged at the top,
and opening to allow the escape of the pollen, as in the Sassafras,
Spice-bush, and Barberry (Fig. 308).

296. =Pollen.= This is the powdery matter, commonly of a yellow color,
which fills the cells of the anther, and is discharged during
blossoming, after which the stamens generally fall or wither away. Under
the microscope it is found to consist of grains, usually round or oval,
and all alike in the same species, but very different in different
plants. So that the plant may sometimes be recognized from the pollen
alone. Several forms are shown in the accompanying figures.

[Illustration: Fig. 309. Magnified pollen of a Lily, smooth and oval;
310, of Echinocystis, grooved lengthwise; 311, of Sicyos, with bristly
points and smooth bands; 312, of Musk Plant (Mimulus), with spiral
grooves; 313, of Succory, twelve-sided and dotted.]

297. An ordinary pollen-grain has two coats; the outer coat thickish,
but weak, and frequently adorned with lines or bands, or studded with
points; the inner coat is extremely thin and delicate, but extensible,
and its cavity when fresh c