EXPLOSIVK FLOWERS. 



265 



or, as iu a few Orchids, the anthers and rostellum. The number of these contri- 

 vances is very large, and I must therefore confine myself to an account of the most 

 curious forms, beginning with the case of Crucianella stylosa, which grows native 

 in Northern Persia, and is represented in figs. 272 and 274 ^ This plant belongs 

 to the StellatsB gi-oup of Rubiacese. Its rose-coloured flowers are conglomerated in 

 terminal heads (274'), and scent the air with honey to a considerable distance. If 

 one side of the coi-olla be removed, the first peculiarities that strike the observer 

 are that the long slender style is twisted into a spiral, and that the thick stigma 



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Fig, 272. — Explosive appaiatus for the transfer oi pollen to the bodies of insects 



' Longitudinal section through the unopened flower of Crucianella stylosa; the papillose stigma wedged between the closed 

 anthers. 2 The same after the dehiscence of the anthers; the pollen deposited on the papillose surface of the stigma. 

 3 The stigma covered with pollen has been carried up owing to the elongation of the style until it rests under the dome of 

 the closed flower. * The corolla has burst open, and the style, springing up suddenly in consequence, is discharging the 

 pollen from the surface of the stigma. 6 The style projects far beyond the corolla and bears the open two-lipped stigma 

 which is now first mature and ready to be pollinated. All the figures X 4. 



at the top of it is wedged between the anthers (see fig. 272 '). The moment the 

 anthers open the pollen pours out of the loculi and rests upon the papillose 

 surface of the stigma (fig. 272 ^). Soon afterwards the style elongates and its coils 

 relax somewhat, the result being that the stigma, with its coating of pollen, is 

 carried up above the now empty anthers until it comes against the dome-shaped 

 top of the closed corolla where its further ascent is stopped. At this stage of 

 development (fig. 272 ^) the style is in a condition of such extreme tension that 

 the instant the limb of the corolla opens it springs up, scattering a cloud of pollen 

 from the surface of the stigma (fig. 272 *). In the absence of insects this ejection of 



