The plants included in this tribe are all considered to bear more or less resemblance to the Rhododendron, though in some of them the family likeness is not very strong; and the genera I shall describe to illustrate it are Rhododendron, Azalea, and Rhodora (the last two being by some botanists included in Rhododendron); Kalmia, Menziesia, and Ledum. [Illustration: FIG. 57.—BACK VIEW OF A FLOWER OF RHODODENDRON MAXIMUM, AND SEED-POD.] [Illustration: FIG. 58.—FLOWER OF RHODODENDRON PONTICUM.] The species of the genus Rhododendron are easily distinguished by their flower buds, which are disposed in the form of a strobile, or pine-cone, each bud having its accompanying bract, which the flower retains after its expansion, as shown in _fig._ 57 at _a_, in a flower of _R. maximum_. There are five or ten stamens of unequal length, the larger ones curling upwards (as shown at _b_ in _fig._ 58), as does the style (_c_), which has a simple stigma. The flowers have a very small calyx, (_d_ in _fig._ 57,) and a campanulate corolla which is deeply five-cleft, the upper segment (_e_ in _fig._ 58) being somewhat larger than the rest, and spotted in the inside. The capsule is five-celled and five-valved, as shown in _fig._ 57 _f_. The leaves of nearly all the species are evergreen; and the flowers are showy, and produced in terminal corymbs. The principal species may be thus distinguished from each other; _R. maximum_ has drooping leaves, covered with brown or white down on the under surface, and a dense corymb of flowers, the segments of the corollas of which are roundish, and the bracts leafy. In _R. ponticum_, on the contrary, the corymbs of flowers are looser, the segments more pointed, and the bracts more scale-like; and the leaves are smooth on both surfaces. The seed-pods also differ: in those of _R. maximum_ and the other American species, the valves are smooth as shown at _f_ in _fig._ 57; and in those of _R. ponticum_, the valves are somewhat crinkled as shown in _fig._ 59. This species, and all its hybrids and varieties, are more tender than _R. maximum_, _R. catawbiense_, and all the other American kinds and their offspring. _R. catawbiense_ has the flower of a darker colour on the outside of the corolla than within, and the upper segment is very faintly dotted. It hybridises freely with _R. arboreum_, which _R. maximum_ does not, and the hybrids thus produced are hardier than those raised from _R. ponticum_, though the latter are by far the most numerous. [Illustration: FIG. 59.—SEED-POD OF RHODODENDRON PONTICUM.]