XVI INTRODUCTION. 



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, arranged regularly round the stem ; geminate, ternate, fascicled, 

 or fasciculate 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 axil- 

 lary 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, 

 botanists 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 principal one, the stem is usually said to have two opposite 

 branches ; umbellate, when divided 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 foot- 

 stalk 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). 



37. Leaves are 



sessile, when the blade rests on the stem without the intervention of a 

 petiole. 



amplexicaul or stem-clasping, when the sessile base of the blade clasps the 

 stem horizontally. 



perfoliate, when the base of the blade not only clasps the stem, but closes 

 round it on the opposite side, so that the stem appears to pierce through the 

 blade. 



decurrent, when the edges of the leaf are continued dow T n the stem so as 

 to form raised lines or narrow appendages, called wings. 



sheathing, when the base of the blade, or of the more or less expanded 

 petiole, forms a vertical sheath round the stem for some distance above the 

 node. 



38. Leaves and flowers are called radical, when inserted on a rhizome or 

 stock, or so close to the base of the stem as to appear to proceed from the root, 

 rhizome, or stock ; cauline, when inserted on a distinct stem. Radical leaves 

 are rosulate when they spread in a circle on the ground. 



39. Leaves are 



