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when the ovule is curved on itself, as in chickweed; amphitropous, when the body of the ovule stands transversely to the stalk; anatropous, when the ovule is inverted and the opening close to the hilum; the ridge extending along the ovule is called the raphe.

The fruit is the matured pistil, including whatever.

parts are attached to it. The seed vessel is called the pericarp. The principal kinds of fruit are: The simple fruit, resulting from the ripening of a single pistil, an example being the bean pod; the simple fruits are divided into the dry fruits, stone fruits and berries; an aggregate fruit formed when a cluster of carpels of a single flower are crowded in a mass, as in the raspberry; and multiple fruit formed by the union of a cluster of Fig. 81. Two cotyledons pistils of several flowers, as in of bean; r, radicle; p, plum- the mulberry. ule. An exalbuminous seed Fruits may also be divided o * into dehiscent and indehiscent. The dehiscent fruits are represented by the legume, a true pod which comes from a simple pistil with dehiscence on both sides, as in the pea and bean; the follicle, a pod formed from a simple pistil and dehiscent by the ventral suture, as in the larkspur; capsule, a dehiscent fruit of a compound pistil. Modifications are a pyris, which opens by a circular line, as in the purslane and plantain; silique, like the pod of the mustard, which has two parietal placentae. The indehiscent fruits are nearly always oneseeded, the more important kinds being the achene (achenium), a one-seeded, seedlike fruit, like that of the sunflower, buttercup and smartweed; samara, a keylike fruit provided with a wing, as in the maple and ash; the utricle, somewhat like an achene, but with a loose membrane,

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as in goosefoot or lamb's quarter; caryopsis, a grain fruit in which the wall of the ovary and the testa are closely united; a nut, a hard one-celled and one-seeded fruit, usually produced from an ovary with two or more cells, as in the hazelnut and acorn; and the paired fruits, as the cremocarp of the parsnip, each half of which is a mericarp. The more important fleshy fruits are represented by the drupes or stone fruit, such as the peach and plum; the pome, as the apple, the fleshy part of which is the enlarged calyx; the pepo or gourd fruit, like the squash; the berry, as the grape, which is fleshy. The fruit of the pine is called the strobile. The Seed.—The seed is the fertilized ovule and consists of the following parts: The funiculus (occasionally lacking) or the stalk; the outer and inner coats—the outer, frequently hard, called the testa, the inner known as the tegmen; the micropyle or place where the pollen tube enters the ovu le; the hilum or scar sh o w in g where the seed

Fig. 82. A, germinating pea; r, root; p, young stem. B. Two was attached

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c, caulicle. (C. M. King.) The albumen y

when present may be all endosperm, as in the starchy part of corn, or perisperm, as in canna; this corresponds to the nucellus of the ovule. Some seeds may contain both Fig. 83. Ger - - 12s. - endosperm and perisperm, as in the pepper. mãì i. Most seeds have a small quantity of peri- Cotyledons j. e main in seed. sperm present. The embryo of the seed gives (C. M. King.) rise to the new plant and consists of the

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radicle, or true root; the caulicle, or stem; and the cotyledons. When there is one cotyledon the plant is monocotyledonous, when two it is dicotyledonous, when three or more, polycotyledonous; the plumule rises from the caulicle. In germination, the cotyledon or cotyledons may remain in the seed, in which case they are said to be hypogaeous, as in the pea; when they are pushed out, as in the bean, they are epigaeous.

Seeds may be smooth, as in the bean; rough, as in corncockle; they may have a thin membrane growing out from the surface, in which case the seed is said to be winged.

Fig. 84.

Fig. 86. Fig. 87.

Fig. 84. Squash seed germinating. Root below and cotyledons pushing out: pp, pumpkin peg holding the testa. (C. M. King.)

Fig. 85. Cross section of buckwheat “seed,” an achenium: e, wall of ovary, inner line represents the testa. Embryo with two cotyledons surrounded by the endosperm; seed albuminous. (C. M. King.)

Fig. 86. Cross section of date seed: en, hard and horny endosperm, embryo small in lower part of seed. Seed albuminous. (C. M. King.)

Fig. 87. A longitudinal section of kernel of corn; an albuminous seed: ce, endosperm; pl. plumule; sc, scutellum; c, caulicle; pr, primary root; h, point of attachment of kernel to cob; rs, root sheath. The darker portion represents the endosperm, light portion embryo or germ. {C. M. King.)

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CHAPTER XIV. DESCRIPTIONS OF SOME COMMON WEEDS

The More Important Families of Weeds.-The weeds described in the following pages are quite widely distributed. Many of them are as common in New England as in the Northern Mississippi valley and many of them are common on the Pacific coast. Some weeds are local, such as the tarweed of California. Those who are especially interested in a further study of the various regions should consult some of the manuals and floras, such as Robinson and Fernald, Gray's “New Manual of Botany” and Britton’s “Manual of Northeastern United States.”

KEYS TO FAMILIES

1. Plants producing spores, in spore cases or sporangia. Rushlike and jointed (Equisetaceae). P. 138. Not rushlike nor jointed (Polypodiaceae). P. 137. Plants producing pollen and ovules, which develop into seeds. 2 2. Embryo of one cotyledon; stem endogenous with no distinction between pith wood and bark; leaves generally par

allel veined (Monocotyledoneae). . . . . . . . . . . . . . . . . . . . . . . . . 3 Embryo usually with two cotyledons; stems with distinct wood

pith and bark; leaves netted veined (Dicotyledoneae)..... 6

3. Flowers with small bracts or scales. . . . . . . . . . . . . . . . . . . . . . . . 4

Flowers with a perianth, petal-like, and having parts colored alike (Liliaceae). P. 159. 4. Scale 1 (Cyperaceae). P. 157. Scales more than one. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Scales in pairs (Gramineae). P. 139. Perianth of six similar scales (Juncaceae). P. 158. 6. Petals absent. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Petals present. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 12 7. Flowers monoecious, dioecious or polygamous. Fruit, a three-lobed, three-seeded capsule. Plants with milky juice (Euphorbiaceae). P. 193. Fruit, one-seeded (Urticaceae). P. 16o. 8. Fruit, not an achene; fleshy plants with a coiled embryo...... 9 Fruit, an achene.

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Flowers with sepals, embryo straight (Polygonaceae). P. 162.
Flowers without floral envelopes (Piperaceae). P. 16o.

Fruit, an utricle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Io
Flowers, with bracts (Amaranthaceae). P. 17o.
Flowers, without bracts.................................... II

The persistent calyx inclosing the fruit (Nyctagineaceae). P. 162.
Calyx not persistent; sepals green or greenish (Chenopodiaceae.)

P. 167.
Flowers, polypetalous. . . . . . . . . . . . . . . . . . . . ................. 13
Flowers, gamopetalous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Stamens numerous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I4
Stamens few, as many as the petals, or not more than twice as

In any . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2O
Calyx free from the ovary; pistil, one or more than one..... I 5
Pistils numerous, or more than one....................... . 16
I istils, one or few. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Stamens inserted on the calyx (Rosaceae). P. 185.
Stamens, monadelphous or diadelphous.
Fruit a legume (Leguminosae). P. 187.
Pistils united into a ring (Malvaceae). P. 136.
Stamens, not monadelphous. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Stamens inserted on the receptacle, leaves not punctate (Ra-
nunculaceae). P. 177.
Stamens inserted on the receptacle in clusters, leaves punctate,
flowers yellow (Hypericaceae). P. 202.
Ovary compound, one-celled; fleshy herbs (Portulacaceae). P. 176.
Ovary compound; pistil one, carpels two or more; plants with
milky or colored juice (Papaveraceae). P. 178.

Calyx free from the ovary. . . . . . . . : . . . . . . . . . . . . . . . . . . . . . . . 2. It
Ovary 1, 2—4-lobed, or entire (Sapindaceae). P. 198.
Ovary 2–5, or more, celled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Leaves dissected (Geraniaceae). P. 191.
Leaves trifoliate (Oxalidaceae). P. 191.
Leaves pinnately compound (Zygophyllaceae). P. 192.

Ovary compound, one-celled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Ovary compound, two or more celled. . . . . . . . . . . . . . . . . . . . . . 25
Flowers, irregular, stamens five (Violaceae). P. 203.

Flowers, regular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Flowers, perfect, regular (Caryophyllaceae). P. 173.
Flowers, monoecious or dioecious (Euphorbiaceae). P. 193.
Ovules, solitary, trees or shrubs (Anacardiaceae). P. 198.
Ovules few, stamens six, tetradynamous (Cruciferae). P. 179.
Ovules few, stamens six, not tetradynamous (Capparidaceae). P. 184.
Ovary 2 to several-celled, stamens 8 or 4 (Onagraceae). P. 204.
Ovules and seeds, only one in each cell, stamens five, flowers
in umbels (Umbelliferae). P. 205.

Calyx free from the ovary, superior. . . . . . . . . . . . . . . . . . . . . . . . 28
Corella, regular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Corolla, irregular . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Ovaries of two carpels. . . . . . . . . . . . . . . . . e - e - a • - e - a • * * * - - - - - 30

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