646 



SCALE-LEAVES, FOLIAGE-LEAVES, FLORAL-LEAVES. 



stand-point the perianth-leaves are, as it were, only antherless stamens, and this view 

 is supported by the fact that in the so-called double flowers the anther-bearing 

 stamens regularly change into antherless perianth-leaves. In the flowers of water- 

 liUes as a rule no sharp limit can be drawn between stamens and perianth-leaves, 

 but a gradual transition from one to the other may be plainly noted. The flowers 

 of certain limes (Tilia Americana, alba, argentea), as well as those of the arrow- 

 grass (Triglochin), of which an illustration is given below, are very instructive in 

 this respect. In the Silver Lime (Tilia argentea, figs. 151 i and 151 ^) a whorl of 



Fig. 161.— Flowers of the Silver Lime (Tilia argentea), and of a species of Arrow-grass (Triglochin Barellieri). 



1 luflorescence of the Silver Lime, natural size. 2 Longitudinal section through a single flower. 8 Flower of the Arrow-grass, 

 in the first stage of hlossoming. * The same flower in a later stage of development ; one of the upper perianth-leaves cut 

 away. 3, s^ and * are enlarged. 



stamens with anthers is first formed below the pistil, followed by a whorl of leaves 

 without anthers, which, however, secrete honey to allure insects; then again comes 

 a whorl of leaves with, and below these again two whorls of leaves without 

 anthers. The same is the case in Triglochin, whose flowers look as if they were 

 composed of two stories standing one above the other, quite similarly arranged (see 

 figs. 151 ^ and 151 ■*). The flower commences below with a whorl of three hollowed 

 antherless leaves; above these comes a whorl of three leaves with anthers, and the 

 large anthers are surrounded and protected during development by the hollowed 

 leaves as if by a hood; then again follows a whorl of three hollowed antherless 

 leaves, and above these yet again a whorl of three stamens with large anthers, an 



