DISPERSAL BY WIND. 



817 



and abundant rhizoids are distributed by wind. This is observed in Mosses of very 

 different genera (e.g. Leucodon sciuroides, Thuidium abietinum, Hypnum rurjosum, 

 Myurella julacea, Conomitrium Julianum, Anoectangium Sendtnerianuvi). The 

 development of this form of offshoot is shown in figs. 156^ and 156^*', p. 23, in 

 Leucodon sciuroides, which is common on the bark of old trees. In the angles made 

 by the leaves with the axis of old shoots, buds first arise which grow into miniature 

 Moss-shoots. These tiny shoots then become loosened at their base, and push up 

 towards the top of the leaves supporting them. This happens more especially in 

 rainy weather. When it is dry their leaflets lie close to the axis, but when saturated 

 with moisture they stand out and bend backwards, and thus raise themselves out of 

 the deep niche in which they have hitherto been concealed. Many of these loosened 

 shoots are without doubt carried away by rain-water, and so transported some 

 little distance, but most of them are whirled off by the wind, and carried far away 

 over mountain and valley. 



Bud-shaped offshoots, which become detached from the aerial portions of plants, 

 and whose distribution is effected by wind, are comparatively rare. A remarkable 

 instance is furnished by the Club-moss Lycopodium Selago (see fig. 343 ^ p. 460). 

 This plant, which is found in mountainous districts in the Northern Hemisphere 

 of the Old and New Worlds, forms buds in the axils of its stiff, dark-green leaves, 

 especially near the top of the shoot, which might, at first sight, be mistaken for 

 small winged fruits. These buds are so provided with little leaves as to ofier a 

 good purchase to the wind, and by this means they are transported (cf. fig. 343^). 

 The North American Lycopodium lucidulum, L. rejiexum, L. Haleakala, L. ser- 

 ratum, L. erubescens, behave in just the same way as Lycopodium Selago, and 

 it is not improbable that many other allied species exhibit this kind of offshoot. 



Most detached bud-like offshoots, which develop in the axils of foliage-leaves 

 and bracts on larger plants, e.g. on the bulbiferous Coral- wort (Bentaria bulbifera; 

 see p. 461), can hardly be said to be distributed by wind. They are spherical 

 or ovate, and not flattened like those of the Club-moss, and they are too cumbrous 

 for transport on the wings of the wind. And yet the wind plays an important 

 part in the distribution in such cases. The bulbils are borne on fairly stiff shoots, 

 and the nature of their attachment is very fragile. Thus, as the shoot rebounds 

 after the blast, many of the bulbils become detached, and are jerked away to a 

 considerable distance. 



There are three types of offshoots which are jerked from the plant in the above- 

 mentioned manner. First, those which have the form of closed buds or small bulbs, 

 and which consist of a very much abbreviated stem or bulb-axis, and a few much- 

 thickened scale-leaves filled with reserve materials. These are found in the 

 bulbiferous Coral-wort, which grows commonly in Central European Beech forests, 

 and has been selected as typical; on the bulbiferous Saxifrage (Saxifraga bulbifera), 

 widely distributed in meadows in Eastern Europe; on several Lilies (e.g. Lilium 

 bulhiferum, tigrinum, and lancifolium); and on the Persian Gagea (Gagea Persica), 

 in the axils of the upper foliage-leaves; on Foucroya gigantea, growing in the 



