INTRODUCTION. Vll 



§ 4. The Stem. 



28. Stems are 



erect, when they ascend perpendicularly from the root or stock ; twiggy or virgate, 

 when at the same time they are slender, stiff, and scarcely branched. 



decumbent or ascending, when they spread horizontally, or nearly so, at the base, 

 and then turn upwards and become erect. 



procumbent, when they spread along the ground the whole or the greater portion 

 of their length ; diffuse, when at the same time very much and rather loosely branched. 



prostrate, when they lie still closer to the ground. 



creeping, when they emit roots at their nodes. This term is also frequently ap- 

 plied to any rhizomes or roots which spread horizontally. 



tufted or ccespitose, when very snort, close, and many together from the same 

 stock. 



29. Weak climbing stems are said to twine, when they support themselves by wind- 

 ing spirally round any object ; such stems are also called voluble. When they simply 

 climb without twining, they support themselves by their leaves, or by special clasping 

 organs called tendrils (169), or sometimes, hke the Ivy, by small root-like excrescences. 



30. Suckers are young plants formed at the end of creeping, underground rootstocks. 

 Scions, runners, and stolons, or stoles, are names given to young plants formed at the 

 end or at the nodes (31) of branches or stocks creeping wholly or partially above- 

 ground, or sometimes to the creeping stocks themselves. 



31. A node is a point of the stem or its branches at which one or more leaves, 

 branches, or leaf-buds (16) are given off. An internode is the portion of the stem com- 

 prised between two nodes. 



32. Branches or leaves are 



opposite, when two proceed from the same node on opposite sides of the stem. 



whorled or verticillate (in a whorl or verticil), when several proceed from the 

 same node,>rranged regularly round the stem ; geminate, ternate, fascicled, or fascicu- 

 late when two, three, or more proceed from the same node on the same side of the 

 stem. A tuft of fasciculate leaves is usually in fact an axillary leafy branch, so short 

 that the leaves appear to proceed all from the same point. 



alternate, when one only proceeds from each node, one on one side and the next 

 above or below on the opposite side of the stem. 



decussate, when opposite, but each pair placed at right-angles to the next pair above 

 or below it ; distichous, when regularly arranged one above another in two opposite rows, 

 one on each side of the stem; tristichous, when in three rows, etc. (92). 



scattered, when irregularly arranged round the stem ; frequently, however, bota- 

 nists apply the term alternate to all branches or leaves that are neither opposite nor 

 whorled. 



secund, when all start from or are turned to one side of the stem. 



33. Branches are dichotomous, when several times forked, the two branches of 

 each fork being nearly equal ; trichotomous, when there are three nearly equal branches 

 at each division instead of two ; but when the middle branch is evidently the princi- 

 pal one, the stem is usually said to have two opposite branches ; umbellate, when di- 

 vided in the same manner into several nearly equal branches proceeding from the same 

 point. If however the central branch is larger than the two or more lateral ones, the 

 stem is said to have opposite or whorled branches, as the case may be. 



34. A culm is a name sometimes given to the stem of Grasses, Sedges, and some 

 other Monocotyledonous plants. 



§ 5. The Leaves. 



35. The ordinary or perfect Leaf consists of a flat blade or lamina, usually green, 

 and more or less horizontal, attached to the stem by a stalk called a footstalk or petiole. 

 When the form or dimensions of a leaf are spoken of, it is generally the blade that is 

 meant, without the petiole or stalk. 



36. The end by which a leaf, a part of the flower, a seed, or any other organ, is 

 attached to the stem or other organ, is called its base, the opposite end is its apex or 

 summit, excepting sometimes in the case of anther-cells (115). 



