856 



THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. 



(e.g. Tillandsia; see fig. 475^) only one pole of the seed is furnished with a tuft of 

 hairs, whilst in Adenium (see fig. 471 -), belonging to the family Apocynacefe, both 

 poles are so provided. In Valerianacese (e.g. Valeriana; see fig. 471 ^) and in 

 Compositae (e.g. Senecio and Taraxacum; see figs. 471 1'^'") the tuft of hairs which 

 acts as a parachute springs from the upper extremity of the achene. Sometimes 

 the parachute and the body it keeps in suspension are connected by a slender stalk 

 (e.g. in Tillandsia and TaraoMcum); but usually the former is directly sessile on 

 one extremity of the seed or indehiscent fruit as the case may be. In Verticordia 

 (see figs. 469 ^•'''^), of the family Myrtaceae, a strange and beautiful parachute is 

 formed by five petals which are in the form of little fans, each composed of ten 



Fig. 470.— Dispersion of traits and seeds by the wind. 

 Bombax. ^ Aneynone sylvestris. ^ Oossypium Barbadense» 



feather-like lobes, and in some Labiatae, as, for instance, Micromeria nervosa (see 

 fig. 471 ''}, the radiating, hair-studded segments of the fruiting calyx constitute a 

 similar apparatus. On the other hand, in several other Labiatse (e.g. Ballota 

 acetabulosa), in many Plumbaginacese (e.g. ÄTnieria; see fig. 468^), and in several 

 Dipsacese (e.g. Scahiosa; see fig. 468^) the parachute is developed from the delicate, 

 dry membranous calyx or from the epicalyx. Nor must reference to the Cape 

 Silver Tree (Leucadendron argenteuTn, one of the Proteaceae) be omitted. The 

 fruits here are produced in large cones not unlike those of the Stone Pine (Pinus 

 Pinea) in form and dimensions. Each bract of the ripe cone subtends a fruit 

 consisting of a nut with persistent wiry style and stigma. The 4-lobed perianth 

 also persists as a membranous parachute, its originally free apices having become 

 connate above the nut and around the style. Ultimately the original attachment of 

 the perianth below the ovary becomes dissolved, and as the nut falls out of the cone 



