COMPARATIVE MORPHOLOGY OF THE CARPEL IN THE ROSACEAE VI. POMOIDEAE: ERIOBOTRYA, HETEROMELES, PHOTINIA, POURTHIAEA, RAPHIOLEPIS, STRANVAESIA

The pomoid genera, Eriobotrya, Photinia, Pourthiaea, Raphiolepis, Stranvaesia , and Heteromeles , have compound inflorescences and biovulate carpels which become papery at maturity. The carpels of all of these except Heteromeles are fused with one another. There are open sutures in the carpels of Heteromeles, Photinia, Pourthiaea , and Raphiolepis , and in these four genera the extent of fusion of the ovular bundle with the wing bundle is related directly to the state of tegumentary fusion and to the extent of fusion of the carpel with the floral cup. In those species of Eriobotrya and Stranvaesia with closed sutures the integuments tend to be fused, as do the ovular and wing bundles, and the carpels are adnate with the floral cup for a considerable distance; in species with open sutures the integuments tend to be free, the ovular and wing bundles tend to be separate, and the extent of fusion of carpel with floral cup tends to be shorter. In genera with connate carpels the wing bundles of adjoining carpels may also be fused. The greatest extent of fusion occurs in Eriobotrya and Raphiolepis , in which there may also be attenuation and disappearance of the wing bundles above the region of ovular insertion and even reduction and disappearance of the carpellary margin.