The flowers of this tribe are called Papilionaceous; because Papilio is the scientific name of a genus of butterflies, which they were supposed to resemble. The type of this tribe may be considered the flower of the sweet-pea (_Lathyrus odoratus_), which has a small green calyx, cut into five deep notches, but not divided into regular sepals. (See _a_ and _b_ in _fig._ 13.) The corolla is in five petals, the largest of which (_c_) stands erect, and is called the vexillum or standard; below this are two smaller petals (_d_), which are called the algæ or wings; and below these are two petals, joined together so as to form a kind of boat (_e_), which are called the carina or keel, and which serve as a cradle for the stamens and pistil. There are ten stamens, nine of which have the lower half of their filaments growing together, so as to form a fleshy substance at the base, as shown in _fig._ 14 at _f_, and the other (_g_) is free. The ovary is oblong, terminating in a filiform style, with a pointed stigma, as shown at _g_ in _fig._ 13; and it is one-celled and many-seeded; the seeds being what we call the peas. When the petals fall, the pod still retains the calyx (_b_), and the style (_g_); and these remain on till the seeds are ripe, when the pod divides naturally into two parts, or valves as they are called, which curl back so as to discharge the seeds. If the pod be examined before it bursts, it will be found that the valves are composed of a fleshy substance, lined with a strong membrane or skin, and that they are united by two seams, called the dorsal and ventral sutures. Along the ventral suture (_h_) there runs a kind of nerve, called the placenta, to which the peas are attached, each pea being furnished with a little separate stalk, called a funicle. A cook would be surprised, even in these enlightened times, to be told to take a legume of _Pisum sativum_, and after separating the two valves at the dorsal suture, to detach the funicles of the seeds from the placenta; yet these scientific terms would merely describe the operation of shelling the peas. It will be seen by this description that the pod of the pea differs very materially from the seed-vessels of all the other plants I have had occasion to describe; and that it thus forms a very distinctive character for the order. The other parts vary in the different genera: the calyx is sometimes tubular, and sometimes inflated; sometimes it has only four notches, or teeth as they are called, instead of five, and sometimes it has five distinct sepals divided to the base. The parts of the corolla vary also in proportion to each other, the keel in some of the Australian plants is as long as the standard; as, for example, in _Kennedia Maryattæ_; and in others the wings are so small as to be scarcely visible. The stamens of many of the species are also free, that is, divided to the base; while in others they resemble those of the sweet-pea, in having nine joined