200 ESSENTIAL ORGANS. STAMENS. 



415. Stamens occasionally become sterile by the degeneration or 

 non-development of the anthers, which, in consequence of containing 

 pollen, are essential for fertilization ; such stamens receive the name of 



staminodia, or rudimentary stamens. In Scrophularia 

 (fig. 346), the fifth stamen, s, appears in the form of a 

 scale ; and in many Pentstemons it is reduced to a fila- 

 ment with hairs, or a shrivelled membrane at the apex. 

 In other cases, as in double flowers, the stamens are 

 converted into petals. In Persea gratissima (fig. 325), 

 two glands, g, are produced at the base of the filament 

 in the form of stamens, the anthers of which are abor- 

 tive. Sometimes only one of the anther-lobes becomes 

 abortive. In many unilocular anthers, the non- 

 development of one lobe is indicated by the lateral 

 346 production of a cellular mass resembling the connec- 



tive. In Salvias, where the connective is distractile, one of the lobes 

 only is perfect or fertile (fig. 333 lf\ containing pollen, the other (fig. 

 333 / s) is imperfectly developed and sterile. In Canna, in place of 

 one of the lobes, a petaloid appendage is produced. 



416. It has been already stated, that the term nectary has been 

 sometimes applied to modified stamens presenting abnormal appear- 

 ances. Thus, in Parnassia palustris, the so-called nectaries are clusters 



of abnormal stamens (fig. 304 ), united by a mem- 

 brane at the base, and ending in glandular bodies 

 like anthers. Staminodia were also called nectaries 

 (fig. 346 s). When treating of the disk, other modi- 

 fications of stamens will be considered. 



417. The stamens, in place of being free and sepa- 

 rate, may become united by their filaments (^[ 399). 

 They may also unite by their anthers, and become 

 syngenesious or synantherous (avv, together, and ym<7/?, 

 origin, or dvd^K, anther). This union occurs in 

 Composite flowers, and in Lobelia, Jasione, Viola, &c. 

 418. Stamens vary in length as regards the corolla. Some are 

 enclosed within the tube of the flower, as in Cinchona, and are called 

 included (figs. 287, 288, 344); others are exserted, or extend beyond 

 the flower, as in Littorella, Plantago, and Exostemma. Sometimes 

 the stamens in the early state of the flower project beyond the petals, 

 and in the progress of growth become included, as in Geranium stria- 

 turn (fig. 347). Stamens also vary in their relative lengths as respects 

 each other. When there is more than one row or whorl of stamens 

 in a flower, those on the outside are sometimes longest, as in Eosacea? 



Fig. 346. Irregular corolla of Scrophularia with a staminodium, s, or abortive stamen in the 

 form of a scale. 



Fig. 347. Bud of polypetalous corolla of Geranium striatum, exhibiting the stamens, e e, at 

 first longer than the petals, p p. 



