sect. I MORPHOLOGY 27 



shoot remains short and becomes flattened or even depressed at the 

 tip. The vegetative cone of the rudimentary flower-bud also undergoes 

 corresponding modifications. The floral leaves, which spring from 

 the floral axis, often grow together, and in many cases become so united 

 with the axis, that it is only possible to discover the different steps 

 of this process by means of thorough phylogenetic and comparative 

 morphological investigation. In most instances the rule seems to hold 

 that axillary buds are not formed within a flower except in cases of 

 abnormal development. 



Shoots and their Order of Sequence. — If the vegetative cone of 

 the primary axis of a plant, after reaching maturity, is capable of 

 reproduction, a plant with but one axis will result, and the plant is 

 designated uniaxial or haplocaulescent. Usually, however, it is not 

 until a plant has acquired axes of the second or third order, when it is 

 said to be diplocaulescent or triplocaulescent, or of the wth order, 

 that the capacity for reproduction is attained. A good illustration of 

 a plant with a single axis is afforded by the Poppy, in which the first 

 shoot produced from the embryo terminates in a flower, that is, in 

 that organ of Phanerogams which gives rise to the embryonic germs. 

 As an example of a plant with a triple axis may be cited the common 

 Plantain, Plantago majm; whose primary axis produces only foliage and 

 scale leaves ; while the secondary axes give rise solely to bracteal 

 leaves, from the axils of which finally spring the axes of the third order, 

 which terminate in the flowers. In the case of trees, only shoots of 

 the nth. order can produce flowers. 



The Habit or General Aspect of Plants is dependent upon their 

 origin, mode of growth, and duration, and upon the peculiar develop- 

 ment of their branch systems. Cormophytes which develop herbace- 

 ous aerial shoots, and persist only so long as is requisite for the 

 development and ripening of their fruit, be it one or several vegetative 

 periods, are called HERBS. Herbaceous plants, however, which, 

 although annually dying down to the ground, renew their existence 

 each year by means of new shoots produced from underground shoots, 

 rhizomes, or roots, are further distinguished as perennials or perennial 

 herbs. Shrubs or trees, on the other hand, have wood}', persistent 

 shoots, which bear fruit repeatedly. Shrubs retain their lateral shoots, 

 so that their branches are formed near the ground ; trees, on the 

 contrary, soon lose their lower lateral branches, and have a main stem 

 or trunk, which bears a crown of branches and twigs. 



In catalogues and descriptions of plants the duration of the period of growth 

 is usually expressed by special symbols : thus indicates an annual ; O a biennial, 

 and 11 h, perennial herb ; ~h is employed to designate both trees and shrubs, and 

 for trees the sign t) is also in use. 



