. Foundations of botany. , rushes and sedges, polygon ams, water-dock,bur-reed, arrowhead, water-plantain, pickerel-weed, alder, button-bush, water-parsnip (^Sium), water-hemlock (^Cicuta), water penny-wort (Hydrocotyle). 451. Distances traversed by Floating Seeds. — Oceancurrents furnish transportation for the longest journeysthat are made by floatingseeds. It is a well-knownfact that cocoa-palms areamong the first plants tospring up on newly formedcoral islands. The nutsfrom which these palmsgrew may readily havefloated a thousand milesor more without examining a cocoanutwith the f
. Foundations of botany. , rushes and sedges, polygon ams, water-dock,bur-reed, arrowhead, water-plantain, pickerel-weed, alder, button-bush, water-parsnip (^Sium), water-hemlock (^Cicuta), water penny-wort (Hydrocotyle). 451. Distances traversed by Floating Seeds. — Oceancurrents furnish transportation for the longest journeysthat are made by floatingseeds. It is a well-knownfact that cocoa-palms areamong the first plants tospring up on newly formedcoral islands. The nutsfrom which these palmsgrew may readily havefloated a thousand milesor more without examining a cocoanutwith the fibrous husk at-tached, just as it fell fromthe tree, it is easy to seehow well this fruit isadapted for transportationby water. There are al-together about a hundreddrifting fruits known, one(the Maldive nut) reach-ing a weight of twenty totwenty-five pounds. 452. Burs. — A large class of fruits is characterized bythe presence of hooks on the outer surface. These aresometimes outgrowths from the ovary, sometimes from. Fig. 270. —Panicle of Tickle-Grass, aCommon Tumble weed. 382 FOUNDATIONS OF BOTANY the calyx, sometimes from an involucre. Their office isto attach the fruit to the hair or fur of passing , as in sticktights (Fig. 272), the hooks are comparartively weak, but in other cases, as in the cocklebur (), and still more in the Martynia, the fruit of whichin the green condition is much used for pickles, thehooks are exceedingly strong. Cockleburs can hardly beremoved from the tails of horses and cattle, into which
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectplants, bookyear1901
