it may burst open irregularly to discharge the seed; or it may open
by a circular line all round, the upper part falling off like a lid; as
in the Amaranth (Fig. 387).

[Illustration: Fig. 385. Fruit (cremocarp) of Osmorrhiza; the two
akene-like ripe carpels separating at maturity from a slender axis or
carpophore.]

[Illustration: Fig. 386. Utricle of the common Pigweed (Chenopodium
album).]

[Illustration: Fig. 387. Utricle (pyxis) of Amaranth, opening all round
(circumscissile).]

363. =A Caryopsis, or Grain=, is like an akene with the seed adhering to
the thin pericarp throughout, so that fruit and seed are incorporated
into one body; as in wheat, Indian corn, and other kinds of grain.

364. =A Nut= is a dry and indehiscent fruit, commonly one-celled and
one-seeded, with a hard, crustaceous, or bony wall, such as the
cocoa-nut, hazelnut, chestnut, and the acorn (Fig. 37, 388.) Here the
involucre, in the form of a cup at the base, is called the CUPULE. In
the Chestnut the cupule forms the bur; in the Hazel, a leafy husk.

[Illustration: Fig. 388. Nut (acorn) of the Oak, with its cup or
cupule.]

365. =A Samara, or Key-fruit=, is either a nut or an akene, or any other
indehiscent fruit, furnished with a wing, like that of Ash (Fig. 389),
and Elm (Fig. 390). The Maple-fruit is a pair of keys (Fig. 391).

366. Dehiscent Fruits, or Pods, are of two classes, viz., those of a
simple pistil or carpel, and those of a compound pistil. Two common
sorts of the first are named as follows:--

367. =The Follicle= is a fruit of a simple carpel, which dehisces down
one side only, i. e. by the inner or ventral suture. The fruits of Marsh
Marigold (Fig. 392), Paeony, Larkspur, and Milkweed are of this kind.

[Illustration: Fig. 389. Samara or key of the White Ash, winged at end.
390. Samara of the American Elm, winged all round.]

[Illustration: Fig. 391. Pair of samaras of Sugar Maple.]

[Illustration: Fig. 392. Follicle of Marsh Marigold (Caltha palustris).]

[Illustration: Fig. 393. Legume of a Sweet Pea, opened.]

[Illustration: Fig. 394. Loment or jointed legume of a Tick-Trefoil
(Desmodium).]

368. =The Legume= or true Pod, such as the peapod (Fig. 393), and the
fruit of the Leguminous or Pulse family generally, is one which opens
along the dorsal as well as the ventral suture. The two pieces into
which it splits are called VALVES. A LOMENT is a legume which is
constricted between the seeds, and at length brea