Group, Angiosperms. Class, Monocotyledones. Order, Liliales. Family, Liliaceæ. Genus, Trillium. Species, grandiflorum. In the same way the position of the toothwort would be indicated as follows: Group, Angiosperms. Class, Dicotyledones. Order, Papaverales. Family, Cruciferæ. Genus, Dentaria. Species, diphylla. But in giving the technical name of the plant only two of these names are used, the genus and species, so that for the toothwort we say _Dentaria diphylla_, and for the white wake-robin we say _Trillium grandiflorum_. =940. Kingdom and Subkingdom.=—Organic beings form altogether two kingdoms, the Animal Kingdom and the Plant Kingdom. The Plant Kingdom is then divided into a number of subkingdoms as follows: 1st, Subkingdom Thallophyta, the thallus plants, including the Algæ and Fungi; 2d, Subkingdom Bryophyta, the moss-like plants, including the Liverworts and Mosses; 3d, Subkingdom Pteridophyta, the fern-like plants, including Ferns, Lycopods, Equisetum, Isoetes, etc.; 4th, Subkingdom Spermatophyta, the seed plants, including Gymnosperms and Angiosperms. Subkingdoms are divided into groups of lower order down to the classes. So there are subclasses, subfamilies or tribes, subgenera, and even subspecies. But taking the principal taxonomic divisions from the greater to the lesser rank, the order would be as follows: Plant Kingdom. Subkingdom, Spermatophyta. Group (not used in a definite sense). Class, Gymnospermæ. Order, Pinales. Family, Pinaceæ. Genus, Pinus. Species, strobus, or, in full, Pinus strobus, the white pine. Group Angiospermæ. I. CLASS MONOCOTYLEDONES. =941. Order Pandanales.=—Aquatic or marsh plants. The cattail flags (Typha) and the bur-reeds (Sparganium), each representing a family. The name of the order is taken from the tropical genus Pandanus (the screw-pine often grown in greenhouses). =942. Order Naiadales.=—Aquatic or marsh herbs. Three families are mentioned here. The pondweed family (Naiadaceæ), named after one genus, Naias. The largest genus is Potamogeton, the species of which are known as pondweeds. Ruppia occidentalis occurs in saline ponds in Nebraska, and R. maritima along the seacoast and in saline districts in the interior. The water-plantain family (Alismaceæ) includes the water-plantain (Alisma) and the arrow-leaves (Sagittaria). The tape-grass family (Vallisneriaceæ) includes the tape-grass, or eel-grass (the curious Vallisneria spiralis). =943. Order Graminales.=—Two families. The grass family (Gramineæ), the grasses and grains. The sedge family (Cyperaceæ), the sedges. =944. Order Palmales=, with one family, Palmaceæ, includes the palms, abundant in the tropics and extending into Florida. Cultivated in greenhouses. =945. Order Arales.=