Perennial herbs with a very _characteristic appearance_ (Fig. 310); the stem is most often short, thick, and crowned by a _rosette_ of many leaves, which are long, often very narrow, _leathery_, stiff, and with a _spiny_ edge; they are usually channeled, completely closing round each other, with their edges forming a tightly closed hollow, in which generally water is collected (this among other things insulates the inflorescence and thus prevents the access of creeping insects, such as ants). The presence of numerous stellate, water-containing hairs often gives the leaves a grey appearance, and the layers of cells beneath the upper epidermis of the lamina form an “aqueous tissue,” which serves as a protection against the rays of the sun and regulates the evaporation. The stomata are often situated in furrows on the underside of the leaf, and hence cause a striped appearance. They _are all American_ (525 species), especially from S. America, where they live partly as epiphytes _on trees_, partly in the _clefts of rocks_, often on the steepest slopes, to which they firmly attach themselves by aerial roots; some are terrestrial. The stem is seldom tree-like or many metres in height (_Puya_, in Chili; _Hechtia_, in Mexico). _The inflorescence_ is a terminal spike, raceme, or panicle, often with large and brightly-coloured floral-leaves. The flowers are without scent. The seeds, in the species whose fruit is a capsule, are often provided with wings (hairs, expansions, etc).--_Ananassa sativa_, Pine-apple (W. Indies, Central America) is cultivated for the sake of its juicy, aromatic fruits, which coalesce with their fleshy bracts and form a large spike-like fruit-cluster (multiple-fruits,[29] Fig. 311) bearing on its apex a leafy shoot, which may be used as a cutting. Seeds very rarely developed.--_Tillandsia_ (_T. usneoides_ is a filamentous, richly branched, rootless epiphyte hanging in masses from trees; Trop. Am.), _Aechmea_, _Billbergia_, _Pitcairnia_, etc. USES. The leaves of the Pine-apple, in its native country, are used for the manufacture of cloth. Order 7. =Hæmodoraceæ.= 120 species; in all parts of the world except Europe; perennial, often tomentose and resembling the Bromeliaceæ, Iridaceæ and Amaryllidaceæ. _Hæmodorum_ (Australia).--To this order belong _Ophiopogon_, _Peliosanthes_, _Sanseviera_, and others.