872 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. 



fias 477 3 - * 5 ), the nutlets of several Boraginacese (e.g. Echinospermum, Cynoglossum, 

 and Caccinia; see figs. 477 6 > 7 ' 19 > 20 ), the several segments of the lomenta of ^schyno- 

 mene patula, the jointed siliquas of Tauscheria lasiocarpa, the schizocarps of some 

 species of the genera Asperula and Galium (e.g. Galium Aparine\ see figs. 477 J 

 and 477 2 ), and the mericarps of many Umbellifer0e (Caucalis, Daucus, Orlaya, 

 Sanicula, 'loriUs; see figs. 477 10 ' n - 12 , and figs. 478 6 ). Other contrivances exist, but 

 are much rarer. Such are the bending of the sepals, when the fruit is ripe, so as to 

 convert the calyx into a claw, as in the genus Rochelia (see fig. 478 8 ), the assump- 

 tion by the teeth of the fruiting calyx of the form of hooked prickles, as in 

 Valerianella echinata and V. hamata, Trifolium spumosum, Ballota rupestris, and 

 Marrubium vulgare (see fig. 478 J ), the presence on the achenes of Composites of 

 1, 2, 3, or 4 hooked prickles in the place of a feathery pappus, as in Bidens bipinnata 

 (see figs. 477 17 and 477 18 ), the barbed character of some perianth-bristles, as in Scirpus 

 lacustris, and the crowning of the hypanthium (expanded receptacle) with hooked 

 prickles, as in Agrimonia (see fig. 47 8 5 ). As instances of the transformation of 

 involucral leaves into hooked bristles or prickles, we may mention Xanthium and 

 Lappa (see figs. 478 13 and 478 17 ); whilst Oryza clandestine^, Paspalum tenue, and 

 Lappago racemosa (see figs. 477 13 and 477 14 ) may be taken as representatives of 

 the Grasses whose glumes are furnished with similar appendages. 



Sometimes the entire fruit has the appearance of a claw, or is armed with large 

 barbs, by means of which it attaches itself to passing animals. This form of adapta- 

 tion is especially striking in the pods of Krameria triandra, Ornithopus, Biserrula, 

 Coronilla scorpioides, and Scorpiurus sulcata (see fig. 478 4 ). The achenes of several 

 Composites (e.g. Rhagadiolus stellatus and Koelpinea linearis) are claw-shaped, and 

 Koelpinea linearis is provided in addition with a crown of sharp, curved barbs at 

 the free extremity of each limb of the claw. In several species of the genus Geum, 

 of which Geum urbanum will serve as an example (see figs. 478 15 and 478 16 ), the 

 terminal portion of the segmented style breaks off when the fruit is ripe, and the 

 remaining part becomes converted into a hooked spine which attaches itself to any 

 object that happens to touch it. Similarly, hooked structures are developed from 

 the styles of several Ranunculaceaa and Pedaliacese. Of the latter the most note- 

 worthy are the fruits of Martynias (Martynia lutea, M. proboscoidea, &c.), which 

 detach themselves from the herbaceous stem when the fruit is ripe the stem being 

 by that time in a decaying condition and lie loose upon the ground. Two long 

 curved clasps, with sharp hooked ends somewhat like the horns of a chamois in 

 form, are developed from the styles, and by means of these the fruits cling to the 

 feet of animals which tread on them. Indeed the whole family Pedaliacese is of 

 interest on account of its multifariously hooked fruits. In addition to Martynia 



already mentioned Harpagophytum belongs here, and several other genera, 



ling a Chinese aquatic, Trapella sinensis. In this plant the fruit is provided 



* long appendages wound up like watch-springs, which must readily hitch 



elves on to the legs of aquatic birds-or possibly even to Fishes and in 



on 2 shorter, sharp, stiff spines, which no doubt preserve the fruits against 



