Staminate Flower of Echinocystis lobata

Abstract

1. The order of appearance of organs in floral ontogeny is sepal, petal, stamen. Carpels are not represented. 2. The growth of floral organs is accomplished by means of both cell division and cell enlargement. Neither of these processes is restricted to a definite meristem or cambium. 3. Sepals are completely separate and therefore there is no calyx cup. Each sepal is traversed by a single bundle which enters from the receptacle. 4. While the petals form a loose corolla tube, each has its own epidermis which completely and distinctly marks it off from its adherent neighbors, and which clearly establishes its individuality. 5. Each petal is traversed by five bundles, all of which enter from the receptacle. All but the median bundle are derivatives of sepal bundles. 6. The completeness of the bisporangiate stamen is believed established by the fact that the tetrasporangiate stamen has its origin in two separate primordia; by the fact that staminodia in the pistillate flower, although disposed like stamen primordia, commonly develop without combining in pairs; and by the fact that Telfairia, with its stamens in an intermediate position between two extremes, clearly shows the homology between a tetrasporangiate stamen and two bisporangiate stamens. 7. Vascular associations between staminodia and perianth members in the pistillate flower indicate that the three stamens are members of two stamen cycles; two are opposite petals and one is opposite a sepal. 8. Each division of the androecium, whether bisporangiate or tetrasporangiate, is traversed by a single bundle. This bundle gives off one branch in the former and two in the latter. It is connected directly with the vascular anastomosis in the base of the receptacle rather than with bundles which supply the perianth. 9. With polypetaly known in the family there remains no longer a reason for including Cucurbitaceae in the Sympetalae. And with the pentacyclic condition known in some members, the family comes to take on more aspects of a highly variable, border-line group.