Another departure from the normal is that in which the juvenile or seedling form of shoot persists in the adult tree; the numerous coniferous plants known as species of Retinospora are examples of this.
It is an annual plant, with hollow, erect, knotted stems, and pro duces, in addition to the direct developments from the seedling plant, secondary roots and secondary shoots (tillers) from the base.
A B In Great Britain the flea beetles (Halticidae) are one of the most serious enemies; one of these, the turnip flea (Phyllotreta nemorum), has in some years, notably 1881, caused more than 500,00o loss in England and Scotland alone by eating the young seedling turnips, cabbage and other Cruciferae.
In 1909 the state legislature passed an act authorizing any city, borough or township of the first class to acquire, subject to the approval of the commissioner of forestry, a municipal forest; and it authorized the distribution of seedling forest trees, at cost, to those who would plant and protect them, for growing private forests.
On germination, however, the fungus behaves in the same way as one which has entered in the seedling stage.
Especially in relation to the origin of the vascular bundles which supply them, favours the view that the scutellum and pileole are highly differentiated parts of a single cotyledon,and this view is in accord with a comparative study of the seedling of grasses and of other monocotyledons.
The ground being prepared and, if necessary, enriched, and the surface made fine and smooth, a hole is made with the dibble deep enough and large enough to receive the roots of the seedling plants without doubling them up, and the hole is filled in by working the soil close to the plant with the point of the dibble.
In delicate cases, such as seedling gloxinias and begonias, it is best to lift the little seedling on the end of a flattish pointed stick, often cleft at the apex, pressing this into the new soil where the plant is to be placed, and liberating it and closing the earth about it by the aid of a similar stick held in the other hand.
The embryo is generally surrounded by a larger or smaller amount of foodstuff (endosperm) which serves to nourish it in its development to form a seedling when the seed germinates; frequently, however, as in pea or bean and their allies, the whole of the nourishment for future use is stored up in the cotyledons themselves, which then become thick and fleshy.
A study of the development of the pitcher, especially in the young pitchers of seedling plants, shows that the inflated portion is a development of the midrib of the leaf, while the wings, which are especially well represented in the terrestrial type of pitcher, represent the upper portion of the leaf-blade which has become separated from the lower portion by the tendril; the lid is regarded as representing two leaflets which have become fused.