Floral Morphology of Arceuthobium americanum

Abstract
The anther of the male flower is unilocular. It is characterized by a system of sterile tissue which represents what is left of the separating portions of a tetra-sporangiate anther. The haploid chromosome number is 14. The stigma of the [female] flower is normally divided to form 4 diagonal lobes. The ovary wall is made up, not of 2 fertile but of 4 sterile carpels. These are diagonally arranged and show varying degrees of fusion. The 2 embryo sacs in the central papilla lie in the orthogonal plane, and therefore must be borne on an inner alternating whorl of orthogonally arranged carpel rudiments. This inner whorl bears not 2 but 4 archesporia, only 1 pair forming embryo sacs. The structure of the gynoe-cium must therefore be represented as G=4[image]4 and not as G = 2. Each embryo sac arises from one of a group of archesporial cells.