. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. THE STEM 63. stems of other phints for support (Fig. 38), and often grow until tliey s[)read their own kM\es abo^'e tliose of the phxnts that they encum- ber. Tlie way in which such climbers bend from side to side until they strike some vertical sup- port may be told in tlie words of Darwin : â {^'7\''-!j')] n â¢"â ''â Twining stem of the Movniug Glory. " When the shoot of a lioji rises from the gvo
. Outlines of botany for the high school laboratory and classroom (based on Gray's Lessons in botany) Prepared at the request of the Botanical Dept. of Harvard University. Botany; Botany. THE STEM 63. stems of other phints for support (Fig. 38), and often grow until tliey s[)read their own kM\es abo^'e tliose of the phxnts that they encum- ber. Tlie way in which such climbers bend from side to side until they strike some vertical sup- port may be told in tlie words of Darwin : â {^'7\''-!j')] n â¢"â ''â Twining stem of the Movniug Glory. " When the shoot of a lioji rises from the gvouiid, the two or three first-forineil interiiodes are straiglit and j-eniain stationary; but the next-formed, whilst very young, may be seen to bend to one side and to travel slowdy around towards all points of the compass, moving like the hands of a clock, with the sun. The nujvement very soon acijuires its full ordinary velocity. From seven observations made during August, ami on another plant during April, the average rate during hot weathei' and during tlie day is two hours eight minutes for each revolution ; and none of the revolutions varied much from this rate. The revolving movement continues as long as the plant continues to grow; but each separate internode, as it becomes old, ceases to ; 74. The revolutions are less rapid at night than in the (hij-time, but arc maintained until some object of sup]^>ort is met with, when the free extremity still goes on revolv- ing and the stem shortly encircles the support. The movement then continues in an u[)«'ard-\Ainding spiral, the coils tightening and the t\\'iner steadily ascending. 75. Most spjecies of twining plants wind in a definite direction. That is, as we hiolc down upon the plant, the revolving tip moves with the hands of a watch lying face upward, in some species; opposite to the hands, in other species. 76. Another class of climbing plants includes those tliat simply clamber in a haphaz
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