This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
A genus of noble-looking plants, so distinct in appearance as to form in themselves a special feature in landscape gardening. They are mostly natives of the Southern States of North America and Mexico, and many of them are quite hardy in our gardens, where they are remarkable for their crowns of rigid flat ensiform leaves and large terminal panicles of white flowers. The stem is either short or almost obsolete, or, as in Y. gloriosa, several feet in height and more or less branched. The campanulate perianth is 6-parted, with the segments nearly equal in size, including 6 stamens whose filaments are dilated, becoming broader upwards. Ovary 3-celled, with 3 sessile stigmas. Capsule hexagonal, many-seeded. This genus, with the Aloes and two or three other genera, constitutes a well-marked tribe of the Liliacece. The name is its Peruvian appellation. Although there are perhaps a score or more of species in cultivation, only about six or eight with their varieties are generally known.
There are three tolerably distinct groups, founded on the characters of the leaves. (1.) Margin of the adult leaves distinctly serrulate.
(2.) Margin of the leaves filamentose.
(3.) Margin of the leaves entire, neither filamentose nor serrulate.
To the first group belong two or three species which are not so hardy and do not flower so freely as the others.
1. Y. aloifolia, having a thick stem which attains a height of 10 feet or more, and usually simple in this country on account of its not flowering. Leaves numerous, ascending, 18 to 24 inches long and about an inch broad, dark green or slightly glaucous, narrowed above the dilated base, with a hard reddish-brown point.
2. Y. Treculeana. - A very distinct and handsome plant from Texas, not yet much known in England, though it has frequently flowered in France. It is also caulescent, and the fully developed leaves are from 3 to 4 feet long by 2 to 3 broad, dark green, strongly mucronate, and regularly serrulate.
The Filamentose series includes several of the hardier species of our gardens whose flowers in early Summer are by no means rare, a season seldom passing without producing them, even from quite young plants. Those commonly cultivated in the open air are all stemless.
3. Y. filamentosa. - One of the most familiar species, popularly known as Adam's Needle-and-Thread. The leaves are very numerous, in a dense rosette, from a foot to 2 feet long and 1 to 2 inches broad, bright green, ghfucous, slightly coriaceous, not sharp-pointed, spreading and at length reflexed. Scape 5 to 6 feet high, much branched; flowers numerous, about 2 inches deep. There is also a pretty variegated variety. Y. stricta is very like this, but smaller in all its parts.
4. F. flaccida, another well-known species similar to the last, but the leaves are of less substance, and when old abruptly turned back from the middle as if broken. The leaves too are longer and more copiously filiferous.
5. F. angustifolia. - A narrow-leaved small plant now rarely seen.
The Entire-leaved group contains the most conspicuous species of the genus.
6. F. gloriosa. - This species has long been in cultivation and has produced several varieties. Stem 6 feet or more high, much branched; leaves numerous, crowded, 18 to 30 inches long and about 3 broad in the middle, narrowed towards both ends, erect, with a concave plicated face and sharp points.
Scape 3 to 4 feet high, much branched; flowers numerous, about 2 inches deep. The principal varieties are glaucescens, like the type, but permanently glaucous; obliqua, leaves and flowers smaller than in the type, the former more or less twisted to one side; superba, leaves more rigid than in the type, panicle denser and hardly half as tall; and a variety with variegated foliage.
7. Y. recurvifolia (fig. 252). - Stem dwarfer but more branched than in the preceding. Leaves more or less curved, not so concave and sharp-pointed as in gloriosa. Panicle large and copiously branched. Y. rufo-cincta is a variety of this species with a reddish-brown margin to the leaves.
Fig. 252. Yucca recurvifolia. (About 1/20 nat. size.)
8. Y. acuminata. - This is perhaps an extreme form of F. gloriosa with a short stem and fewer leaves about 2 feet long, sharp-pointed, narrowed towards both ends, and brown or grey on the edge. Scape 3 to 4 feet high; flowers 2 inches deep.