Elementary botany (1898) Elementary botany elementarybotany00atki Year: 1898 SEED DISTRIBUTION. 371 thus exposed. The dark brown achenes stand over the surface of the recep- tacle, each one tipped with the long slender beak of the ovary. The 'pap- pus,' which is so abundant in many of the plants belonging to the composite family, forms here a pencil-like tuft at the \>A ^ tip of this long beak. Vw^j' As the involucral bracts dry and curve down- ward, the pappus also dries, and in doing so bends downward and stands outward, brist- ling like the spokes of a fairy wheel. It is an interesting
Elementary botany (1898) Elementary botany elementarybotany00atki Year: 1898 SEED DISTRIBUTION. 371 thus exposed. The dark brown achenes stand over the surface of the recep- tacle, each one tipped with the long slender beak of the ovary. The 'pap- pus,' which is so abundant in many of the plants belonging to the composite family, forms here a pencil-like tuft at the \>A ^ tip of this long beak. Vw^j' As the involucral bracts dry and curve down- ward, the pappus also dries, and in doing so bends downward and stands outward, brist- ling like the spokes of a fairy wheel. It is an interesting coincidence that this takes place simultaneously w i t h the pappus of all the seeds of a head, so that the ends of the pappus bristles of ad- joining seeds meet, forming a many-sided dome of a delicate and beautiful texture. This causes the beaks of the achenes to be crowded apart, and with the leverage thus brought to bear upon the achenes they are pried off the receptacle. They are thus in a position to be wafted away by the gentlest zephyr, and they go sailing away on the wind like a miniature parachute. As they come slowly to the ground the seed is thus carefully low- ered first, so that it touches the ground in a position for the end whicl contains the root of the embryo to come in contact with the soil. Fig. 473. Lactuca scariola.
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