There are many cases in which the forms proper to a juvenile condition of the plant are retained for a much longer period than ordinary, or even throughout the life of the individual growth goes on, but "development" is checked. Such conditions may even be propagated by seed or bud. It is a very general thing for botanists to consider these cases as reversions to a simpler, primitive type, and this may be so; but on the other hand, they may be degenerations from a complex type, or they may have no direct relation to any antecedent condition. Stasimorphic changes affecting principally the relative size of organs--such, for instance, as the non-development of internodes, or the atrophy or suppression of parts will be found mentioned in the sections relating to those subjects. In the present part those alterations which affect the form of organs principally are treated of.
The retention in adult life of a form characteristic of an early stage of development, and therefore usually transient, may be manifested in any of the organs of the plant. As these cases are for the most part treated under separate headings, it is here only necessary to allude to a few, which it is difficult to allocate satisfactorily, while the reader may be referred for other instances of like nature to the sections on Peloria, Atrophy, Suppression, Dimorphy, Substitutions, &c.
[Illustration: FIG. 115.--_Juniperus sinensis_. Two forms of leaves on branches of the same shrub.]
=Stasimorphy in the leaves of conifers.=--In many conifers the leaves produced in the young state of the plant are different, both in arrangement and form, from those subsequently developed (see pp. 89, 90). But it occasionally happens that the plant continues to form throughout its existence leaves such as are usually produced only in a young state; thus M. Gubler ('Bull. Soc. Bot., Fr.,' vol. viii, 1861, p. 527) describes a plant of _Pinus pinea_ in which the primordial, usually transitory, foliage was permanent, leaves of the ordinary shape not being developed at all. It more often happens that some only of the leaves retain their young form while others assume other shapes, see fig. 115. This happens frequently in the larch and constantly in the Chinese juniper when it has arrived at a considerable age. In _Cupressus funebris_ two forms of leaves may often be found on the same plant, the one representing the juvenile state, the other the more developed condition. What is very singular, is that a cutting taken from the branch with leaves of the young form grows up into a shrub bearing leaves of no other shape, so that an ordinary observer unacquainted with the history of the plant would imagine that he had to deal with two distinct species. This fact is the more interesting when compared with the alternation of generations which takes place among the lower animals.