The western dry areas have the old-world leguminous Astragalus and Prosopis (Mesquit), but are especially characterized by the northward extension of the new-world tropical Cactaceae, Mgmmillaria, Cereus and Opuntia, by succulent Amar llideae such as A gave (of which the so-called American aloe is a type), and by arborescent Liliaceae (Yucca).
Most veins are usually easily traced, but in the case of succulent plants, as Hoya, agave, stonecrop and mesembryanthemum, the veins are obscure.
Cotyledon, a widely distributed genus with about 90 species, is represented in the British Isles by C. Umbilicus, pennywort, or navelwort, which takes its name from the succulent peltate leaves.
Beetles and larvae are frequently carnivorous in habit, hunting for small insects under stones, or pursuing the soft-skinned grubs of beetles and flies that bore in woody stems or succulent roots.
But the occluding callus is a mass of delicate succulent cells, and offers a dainty morsel to certain insects e.g.
The Alternantheras, Amaranthuses, Iresines and Coleus Verschaffelti furnish high and warm colours; while Pyrethrum Parthenium aureum yields greenish-yellow; Thymus citriodorus aureus, yellowish; Mesembryanthemum cordifolium variegatum, creamy yellow; Centaureas and others, white; Lobelia Erinus, blue; and the succulent Echeverias and Sempervivums, glaucous rosettes, which last add much to the general effect.
When watering becomes necessary for kitchen-garden crops, the hose should be laid on and the lines of esculents allowed to drink their fill, if fresh succulent vegetables are desired.
When cellular tissue is developed to a great extent, leaves become succulent and occasionally assume a crisp or curled appearance.
Similarly, the small amount of cuticular and of epidermal protection, and of lignification in succulent halophytes may also be related to the same circumstance.
Communis, forms a succulent mass of roundish or ovate form, from I ft.