262 The Scottish Naturalist. 



an umbrella about halfway between the base and the apex. In 

 all these cases the wing of the carpel is small in, or even absent 

 from, the flower, becoming developed only as the ripening of the 

 seed advances. 



Less frequently, very rarely indeed in British plants, the 

 carpel becomes covered with a growth of long hairs, which form 

 a float to support it in the air. In Dryas octopetala and in Cle- 

 matis among native plants, and in various foreign species of 

 different genera, the style, instead of falling off after the ovules 

 are fertilised, increases much in size, and becomes converted 

 into a float by the growth of long hairs all over it. 



In many plants the outer envelopes of the flower — viz., corolla 

 and calyx, or the flower-stalk or bract (i.e., the leaf between 

 which and the stem the flower grows out) — may become or may 

 bear the adaptation for wind-carriage. The outer envelope or 

 calyx is the part most frequently modified. If the calyx arises 

 from the flower-stalk below the base of the ovary, and is free 

 from the ovary, it may become much enlarged and bladdery, so 

 as to surround the fruit, and to leave a large empty space be- 

 tween, rendering the whole body light. Such an arrangement 

 may occur in plants with a calyx of coherent sepals (e.g., Tri- 

 folium fragiferum), or with a calyx of free sepals {e.g., Rumex). 

 In some foreign plants (e.g., Gyrocarpus) two or more sepals 

 may become much enlarged so as to form apparent wings; this 

 may be the case in superior as well as in inferior calyces. 



In superior calyces, or those which arise apparently from 

 around the top of the ovary, the modifications met with are 

 greater than in inferior calyces, and are also more frequently 

 met with; but, as in them, become conspicuous only as the 

 seeds ripen. In some plants the calyx spreads out like an 

 umbrella, or like scales or plates, which buoy the fruit up, and 

 render its fall slower. Most Composites (dandelion, thistles, &c.) 

 and some allied groups — e.g., Valeriana, have the calyx repre- 

 sented by the pappus, a spreading crown of hairs arising (as in 

 thistles) directly around the top of the ovary, or (as in the dande- 

 lion and goat's beard) supported on along beak that extends from 

 the upper end of the ovary. These hairs may stand in one or 

 in several rows, and may be simple or more or less branched. 

 Their efficacy in floating the fruits is probably familiar to every 

 one. In the cotton-grasses (Eriophorutri) we meet with a similar 

 modification in the floral envelopes. These consist of merely 

 some slender hairs, which in the flower are quite small. As the 



