108 MORPHOLOGY OF THE ANGIOSPERMS 



THE STAMEN 



The stamen, or microsporophyll, in contrast with the other floral 

 appendages, is typically a slender organ, unleaflike in form. But it is, 

 like the other organs, basically of leaf rank and is closely similar to all 

 these organs in morphological and anatomical structure, in ontogeny, 

 and in its relation to the stem (floral receptacle). Less important re- 

 semblances are in the epidermis: stomata are frequent on the connective 

 — less common on the filament and absent on terete forms; and epi- 

 dermal appendages like those of other floral organs are occasionally 

 present, even over the anther sacs, as in Cahjcanthus jeHilis. With the 

 exception of the primitive laminar types, the stamen shows little super- 

 ficial resemblance to the megasporophyll, the carpel, but the homology 

 of the two organs is usually unquestioned. 



In most families, the stamen is a highly specialized organ, with great 

 variety of elaborate form related to methods of pollination. Typically, it 

 consists of two more or less distinct parts: a proximal, sterile part, the 

 filament; and a distal, fertile part, the anther (Fig. 49P). The anther 

 consists of the microsporangia and the sterile tissues between and 

 within which the sporangia are borne. The term connective is usually 

 applied to the strip of tissues that lies between the pairs of sporangia, 

 but this median strip is not separable, histologically or morphologically, 

 from the tissues of the anther-sac wall, which enclose the sporangia. The 

 stamen is usually considered a rather simple organ, but its simplicity 

 is false; it is, in general, more complex and more reduced than the 

 carpel. Filament and anther are usually distinct, but in the more primi- 

 tive families there may be no clear limitation of fertile and sterile parts. 

 The filament merges into the anther (Fig. 49E to H). The connective 

 may extend beyond the sporangia, sometimes forming a more or less 

 distinct appendage (Fig. 49 A, B, F, I, K). The filament, the connective, 

 and the appendage of the connective constitute continuous parts of the 

 microsporophyll and are not morphologically distinct units. The con- 

 nective is the sterile median part of the anther, connecting and, in 

 various degrees, embedding the sporangia. Morphologically, it repre- 

 sents a median part of the laminar sporophyll. 



The Primitive Stamen 



Like the primitive carpel, which has no distinction of ovary, style, 

 and stigma, the primitive stamen has no distinction between filament 

 and anther. The most primitive stamens in living angiosperms are 

 probably those of some of the woody Ranales (Fig. 50). These are 

 broad, more or less leaflike organs, without, or with weak, distinction 

 between fertile and sterile parts. The sporangia are borne near the 



