Nature and development of plants . g stamens and pistil; w, wings which arch over the standard, , corolla removed, showing the ten stamens surrounding the simple pistil. 420 THE ROSALES very easy transition from the regular flower of the plum to thehighly modified flowers of the pea family. (b) The Pea Family, Papilionacede.—The pea family () is the highest of the rose order and the largest family, withone exception, of all the angiosperms, comprising over 11,000species. Here we find the same type of flower as in the standard family, however, incloses the wings and
Nature and development of plants . g stamens and pistil; w, wings which arch over the standard, , corolla removed, showing the ten stamens surrounding the simple pistil. 420 THE ROSALES very easy transition from the regular flower of the plum to thehighly modified flowers of the pea family. (b) The Pea Family, Papilionacede.—The pea family () is the highest of the rose order and the largest family, withone exception, of all the angiosperms, comprising over 11,000species. Here we find the same type of flower as in the standard family, however, incloses the wings andthe stamens, usually ten in number, may be distinct as notedabove or united by their filaments into a sheath about the soli-tary pistil, more frequently a single stamen remains free, anarrangement called diadelphous (two brotherhoods). This typeof flower is called papilionaceous from its fancied resemblanceto a certain genus of butterfly, Papilio. The more importantcharacteristics of this form of flower are very well illustrated. Fig. 316. Structure of the sweet pea (Lathynts) : A, flower of the pea—c, calyx; s, standard enclosing the two wings, w; k, keel. B, section offlower, showing the sporophylls concealed in the keel. C, one of the , perianth removed, showing relation of sporophylls. in the pea (Fig. 316). The standard is the conspicuous andmost highly-colored organ of the flower, overlapping the twowings which in turn practically cover the keel. By carefullyremoving the keel and wings, it will be seen that these organsare attached to the calyx and receptacle by rather narrow claws(Fig. 316, C) and that they are also locked together by a littleprocess on each wing that fits into a groove on the keel. Nineof the filaments, the tenth being free, form a sheath about theovary which terminates in a stylar brush of upwardly pointinghairs and in a stigma. The anthers and style are confined in DEVELOPMENT OF PLANTS 421 the tip of the keel (Fig. 316, B, D). The signific
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