94 THE FLOWERING PLANT. 



long and two short (didynamous). It will be remembered that 

 in this flower the odd petal is anterior, and there should, there- 

 fore, be an odd posterior stamen, since the outer whorl of stamens, 

 which alternate with the petals, is retained. This, however, is 

 almost always absent. Very rarely, however, a minute stamen 

 is found in this position. Snapdragon is a similar case. Take 

 one of its flowers, and carefully split open the gamopetalous 

 corolla along one side. Upon spreading it out, you will find in 

 its posterior side (i.e., next the stem and opposite the rounded 

 swelling at the base of the corolla tube), near its attachment to 

 the receptacle, a minute white projection. This is the remains 

 of the lost fifth stamen. The foxglove, a near ally, possesses 

 four stamens and no rudiment, while pentastemon, a common 

 garden flower related to this, possesses a very large fifth stamen, 

 devoid, however, of an anther, which curves down to the lower 

 side of the flower. Finally, mullein, also a relative, has five 

 perfect stamens. The speedwell, which belongs to the same 

 group of flowers, presents still further reduction. The sepals 

 and petals are four, but the stamens only two. In most orchids 

 there is only one perfect stamen, the anterior one of the outer 

 whorl. One orchis, however, ladies'-slipper (Cyp/ipedium), has 

 two stamens, belonging in this case to the inner whorl. These 

 facts, and the presence of more or less complete rudiments of 

 other stamens (cf. p. 88), lead to the conclusion that the one- 

 stamened orchis is descended from forms which possessed six 

 perfect stamens, arranged in two alternating three-membered 

 whorls, as, for example, in snowdrop and lily (fig. 38). Stamens 

 are absent altogether in female or pistillate jioivers, and this often 

 appears to be the result of reduction. Some of the flowers on 

 certain plants are neuter, i.e., devoid altogether of sporophylls, 

 and reduction has undoubtedly taken place in such cases. 



Stamens are sometimes increased in number in cyclic flowers, 

 instead of being reduced. In the wallflower, for instance, there 

 are four sepals and four petals, but six stamens — four long and 

 two short (tetradynamous). The petals are diagonally placed, 

 while the short stamens are lateral in position, and the long ones 

 are grouped in two pairs, one anterior and the other posterior. 

 Each pair appears to have arisen by the splitting of a single 

 stamen. This is supported by the fact that in some tetradynamous 

 flowers a partly-split stamen is occasionally found instead of a 

 pair. Branching may also occur. In St. John's wort there are 

 three or five groups of stamens, each group of which has been 

 formed by the branching of a single stamen at an early stage of 

 development. Mallows and hollyhocks, again, possess numerous 

 stamens formed by the branching of five original ones. The terms 



