Elementary botany . many of the plants belonging to the compositefamily, forms here apencil-like tuft at the (,f£ ^ tip of this long beak. M*M^j As the involucral bractsdry and curve down-ward, the pappus alsodries, and in doing sobends downward andstands outward, brist-ling like the spokes ofa small wheel. It is aninteresting coincidencethat this takes placesimultaneously withthe pappus of all theseeds of a head, sothat the ends of thepappus bristles of ad-joining seeds meet,forming a many-sideddome of a delicate andbeautiful texture. Thiscauses the beaks of theachenes to be crowdedapart, and
Elementary botany . many of the plants belonging to the compositefamily, forms here apencil-like tuft at the (,f£ ^ tip of this long beak. M*M^j As the involucral bractsdry and curve down-ward, the pappus alsodries, and in doing sobends downward andstands outward, brist-ling like the spokes ofa small wheel. It is aninteresting coincidencethat this takes placesimultaneously withthe pappus of all theseeds of a head, sothat the ends of thepappus bristles of ad-joining seeds meet,forming a many-sideddome of a delicate andbeautiful texture. Thiscauses the beaks of theachenes to be crowdedapart, and with theleverage thus brought tobear upon the achenesthey are pried off thereceptacle. They arethus in a position tobe wafted away by thegentlest zephyr, andthey go sailing awayon the wind like aminiature they come slowlyto the ground the seedis thus carefully low-ered first, so that it touches the ground in a position for the end whichcontains the root of the embryo to come in contact with the Fig. 483-Lactuca scariola. 462 RELATION- TO ENVIRONMENT. 897. The milkweed, or silkweed.—The common milkweed, or silkweed(Asclepias cornuti), so abundant in rich grounds, is attractive not only WE^^ W^K^m mpR\;-- ^m ^^s^ ^^B J£r * 4^ ^•jSshH mi9 ? ^^mm ?9 ,iWaH JBI &.- - * r&/ ^ *S^HBdw m ?:$£>«* •* % •:•; 8 #? #^ *. 351 IttLv \ # # ^teiMl flUBST l^iJ* ^b«v» • 4 T > € a * c^lySfll Hu ?!&•••- ^^fibtti I - U Fig. (Asclepias cornuti); dissemination of seed. because of the peculiar pendent flower clusters, but also for the beautifulfloats with which it sends its seeds skyward, during a puff of wind, to finallylodge on the earth. 898. The large boat-shaped, tapering pods, in late autumn, are packedwith oval, flattened, brownish seeds, which overlap each other in rows likeshingles on a roof. These make a pretty picture as the pod in drying splitsalong the suture on the convex side, and exposes them to view. The silkytufts
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Keywords: ., bookauthoratk, bookcentury1900, bookdecade1900, booksubjectbotany
