The student must, of course, make himself familiar with the primary divisions of the vegetable kingdom. These are considered in order below. By far the biggest and the most important is that of the Angiosperms. They will be treated first.
Angiosperms: Dicotyledons
The division Angiosperms (Vol. 2, p. 9) includes all those flowering plants whose seeds are enclosed in capsules. This division is again divided into two classes: the Dicotyledons (Vol. 8, p. 185), which are distinguished by the presence of a pair of seed-leaves or cotyledons in the embryo contained in the seed; and the Monocotyledons (see Vol. 2, p. 13), which contain only one. The former embraces most of the flowerbearing plants, and includes the following families:—Boraginaceae (Vol. 4, p. 242) to which order belongs such plants as forget-me-nots, borage, heliotrope, etc. Caprifoliaceae (Vol. 5, p. 290), which include elder, honeysuckle, etc. Caryophyllaceae (Vol. 5, p. 439), with the pinks, carnations, etc. Compositae (Vol. 6, p. 811), which is the largest order in this division and includes one-tenth of the whole number of flowering plants, with such varieties as lettuce, dandelion, artichoke, sunflower, chrysanthemum, etc. Convolvulaceae (Vol. 7, p. 67), among which are the convolvulus, sweet potato, bindweed. Crassulaceae (Vol. 7, p. 380), which include a quantity of African plants. Cruciferae (Vol. 7, p. 521), with the wallflower, stock, mustard, cabbage, radish, nasturtium, etc. Cucurbitaceae (Vol. 7, p. 611), among which are the cucumber, melon, etc. Cupuliferae (Vol. 7, p. 635), with the hazel, oak, beech, alder. Ericaceae (Vol. 9, p. 739), with the rhododendron, arbutus, whortleberry, heather. Euphorbiaceae (Vol. 9, p. 892), which include the castor-oil plant, box, euphorbia, etc. Gentianaceae (Vol. 11, p. 601), with the gentian, yellow-wort, bog-bean, etc. Geraniaceae (Vol. 11, p. 762), whose name is derived from the geranium. Labiatae (Vol. 16, p. 3), with peppermint, marjoram, thyme, sage, ground-ivy. Leguminosae (Vol. 16, p. 381), which embrace gorse, furze, scarlet runner, mimosa, acacia, rest-harrow, etc. Malvaceae (Vol. 17, p. 517), with the mallow, hibiscus, hollyhock. The Moraceae (Vol. 18, p. 814), with the fig, mulberry, banyan, etc. Onagraceae (Vol. 20, p. 104), including the evening primrose, fuschia, etc. Polygonaceae (Vol. 22, p. 26), with dock, rhubarb, buckwheat, etc. Primulaceae (Vol. 22, p. 341), including primrose, cowslip, pimpernel. Ranunculaceae (Vol. 22, p. 895), with the varieties buttercup, clematis, aconite, larkspur, columbine, marsh marigold, anemone. Rosaceae (Vol. 23, p. 722), to which the rose gives the name, and which include strawberry, raspberry, apple, pear, plum, spiraea, blackthorn, etc. Rubiaceae (Vol. 23, p. 808), with gardenias, chincona, coffee, madder. Saxifragaceae (Vol. 24, p. 263), saxifrage, japonica, gooseberry, hydrangea. Scrophulariaceae (Vol. 24, p. 485), with veronica, foxglove, snapdragon, etc. Solanaceae (Vol. 25, p. 356), which embrace henbane, tobacco, deadly nightshade, cape gooseberry, capsicum. Umbelliferae (Vol. 27, p. 575), to which belong ivy, carrot, hemlock, celery, caraway, parsley. Urticaceae (Vol. 27, p. 805), which include the nettle tribes.
Angiosperms: Monocotyledons
The Monocotyledons include the Alismaceae (Vol. 1, p. 671), to which belong the arrow-head, the water plantain, the butomus (so called because the leaves cut the tongues of oxen feeding on them), and other water plants. Aroideae (Vol. 2, p. 640), so called from the Arum family. The Bromeliaceae (Vol. 4, p. 632), including pineapple, Spanish-moss. Cyperaceae (Vol. 7, p. 692), with bulrush, cotton grass, etc. Grasses (Vol. 12, p. 369), a most valuable article. Hydrocharideae (Vol. 14, p. 112), which include a number of water plants. Iridaceae (Vol. 14, p. 793), which include besides the iris, the crocus, gladiolus, etc. The Juncaceae (Vol. 15, p. 555), or Rush family; and the Liliaceae (Vol. 16, p. 683), which include asparagus, hyacinth, star of Bethlehem, fritillary, bluebell, etc.
Other Divisions
Another big division is that of the Gymnosperms (Vol. 12, p. 754). These have naked seed pods; that is to say, the seeds are not enclosed in capsules. The best known and largest division of this class contains the conifers: pines, firs, cedars, larches, etc.
Pteridophyta (Vol. 22, p. 605), or spore-producing plants, including the fern families as the largest and most important of its members.
Bryophyta (Vol. 4, p. 700), the second great sub-division of the vegetable kingdom, comprises the mosses and liverworts.
Algae (Vol. 1, p. 585), plants usually devoid of differentiation into roots, stem, and leaf, coming under the general class of Bryophyta, and including sea-weeds as the main group.