. Introduction to structural and systematic botany, and vegetable physiology. Botany. â upper surface of a folded leaf cohere, those of some other plants ex- hibit a cohesion by their contiguous edges, and give rise to a differ- ent anomaly. This is illustrated by peltate leaves (Fig. 248), and more strikingly by what are termed perfoliate leaves. These in some cases originate from the union of the bases of a pair of opposite sessile leaves {con- nate-perfoliate), as in Silphium perfoliatum, Triosteum perfo- liatum, and the upper pairs of true Honej^suckle (Fig. 294). In others they con- sist
. Introduction to structural and systematic botany, and vegetable physiology. Botany. â upper surface of a folded leaf cohere, those of some other plants ex- hibit a cohesion by their contiguous edges, and give rise to a differ- ent anomaly. This is illustrated by peltate leaves (Fig. 248), and more strikingly by what are termed perfoliate leaves. These in some cases originate from the union of the bases of a pair of opposite sessile leaves {con- nate-perfoliate), as in Silphium perfoliatum, Triosteum perfo- liatum, and the upper pairs of true Honej^suckle (Fig. 294). In others they con- sist of a single clasping leaf, the posterior lobes of which encompass the stem and cohere on the opposite side, as is seen in Bu- pleurum rotundifolium, Uvularia perfo- liata, and Baptisia perfoliata (Fig. 293). 296. leaves with no distinction of Blade and Petiole. The leaves of the Iris, as weU as those of the Daffodil, the Onion, and of many other Endogens, show no distinction of blade and petiole. In some the leaf of this sort may be regarded as a sessile blade ; in others, rather as a petiole per- forming the functions of a blade. Leaves are not always expanded bodies. Sometimes they are filiform or thread-shaped, as those of Asparagus : some are acicular, acerose, or needle-shaped, as in Pines and Larches (Fig. 212, 213) ; others are subulate or awl-shaped, as in Juniper, &c. The Red Cedar and Arbor Vitse (Fig. 295) exhibit both awl-shaped and scale-shaped leaves on different branchlets. 297. Succulent or Fleshy Leaves, like those of Stonecrop, House- leek, Mesembryanthemum or Ice-Plant, and the Agave or Century- Plant, usually assume shapes more or less unlike ordinary foliage. Some of them are terete, hke stems, or at least have no distinct upper and lower surface. These greatly thickened leaves serve a FIG. 293. Perfoliate (single) leaves of Saptisia perfoliata. FIG. 294. Connate-perfoliate leaves of a wild Honeysuckle (Lonicera iiava).. Please note that these images a
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Keywords: ., bookauthorgra, bookcentury1800, bookdecade1850, booksubjectbotany
