454 



FRUITS REPLACED BY OFFSHOOTS. 



offshoots. Similar in its behaviour is another Composite, the alpine Adenostyles 

 Cacaliai. It blossoms and fruits in sub-alpine forests even up to the tree limit, but 

 in high alpine regions, above 2200 metres in altitude, it never flowers, but forms 

 offshoots, and in this way fills little depressions on alpine slopes with its vigorous 

 foliage. The terrestrial form of Polygonum amphibium occurs in a little bog 

 close to my country house in the Gschnitzthal in the Tyrol at a height of 1200 

 metres. For twenty-eight years I have examined this bog every year without ever 

 finding a ripe fruit upon these plants. But it propagates itself with rare luxuriance 

 by means of offshoots and forms a broad girdle around the bog. These plants, 

 Nardosmia frigida, Adenostyles Cacalice, and Polygonum amphibium, grown in 

 a more favourable climate, produce good seed, but their vegetative methods of 

 propagation are so restricted that one might almost suppose them to be different 

 species of plants. 



Instances in which flowers are replaced by offshoots or bulbils in the inflores 

 cence may be mentioned in connection with the above. Polygonum viviparum 

 and bulbiferum, Saxifraga cernua, nivalis, and stellaris, Juncus alplmts and 

 supinus, and the Grasses Aira alpina, Festuca alpina and riipicaprina, Poa 

 alpina and cenisia occur, it is true, with normally developed flowers and fruits, 

 but in alpine, and especially in arctic regions, where these plants have their head- 

 quarters, one very frequently finds purely vegetative buds or bulbils, which become 

 detached from the parent plant and give rise to new individuals, in place of flowers 

 and fruit. In the Polygonums mentioned little bulbils replace a portion of the 

 flowers. Saxifraga cernua usually produces a single terminal flower at the end of 

 its inflorescence, the lateral flowers being replaced by little tufts of bud-like offshoots 

 on short stalks (see fig. 342 ^). These buds, when they fall off, are either still closed 

 (fig. 342 =), or their thick, fleshy, outer scales are already parted, exposing a little 

 green foliage-leaf. On the ground they soon produce roots and grow into new 

 plants (see figs. 342 ^ and 342 "). In Saxifraga nivalis little shoots are formed in 

 place of flowers, each bearing a tuft-like rosette of minute leaves (fig. 342 '). These 

 rosettes are readily separable, and producing roots from their abbreviated axes, 

 give rise to new plants. So also in the Juncuses and Grasses mentioned, little 

 shoots replace the fruits and come away from the inflorescence. These shoots are 

 produced in Poa alpina (see fig. 342 ») and in most of the other Grasses mentioned, 

 in the following manner. The axis of each spikelet, after producing several glumes 

 at its base, forms green leaves above— as it were a grass-plant in miniature (see figs. 

 342 '■• and 3421"). Later, these disarticulate, take root, and grow into new plants. 

 More rarely do shoots arise laterally on the axis, in the axils of subtending scales; 

 when this is the case they fall away in the usual manner. The earlier Botanists 

 termed all such Grasses, and indeed all plants which produce bulbils in their inflor- 

 escences, viviparous, the idea being, that in all of them the seeds germinated 

 precociously whilst still attached to the parent. This view was probably suggested 

 by the common experience of agriculturalists that Rye, Oats, and other cereals 

 sometimes " sprout ", i.e. that when the spikes are continually wetted by rain about 



