The form of root most often found on plants is the fibrous root, made up of numerous branching rootlets or fibres. The thick, fleshy, horizontal root found on most perennials is called the rootstalk; the plant stem grows in new positions each year, leaving scars to denote the locations of stems of previous years. Many grow from round Bulbs, composed of over-lapping fleshy scales; others have solid, fleshy bulbs, or Corms. Often roots give off what are called Stolens, underground running roots that at intervals throw up new plants and form new roots.
A Simple stem is one that rises from the root, with no branches before the flower or flower-cluster is reached. Stems are Erect when they are stout, stiff or perfectly capable of maintaining themselves in an upright position. They are Reclining when they are too weak to hold themselves erect. They are Prostrate or Creeping when they run along the ground, rooting at intervals, or from angles of the leaves; such stems usually turn up at the end or give off erect flowering branches. A plant is called stemless when the leaves all radiate from the base; in such cases the stalk bearing the flowers is the Scape.
Leaves are Linear when they are exceedingly narrow compared to their width, and the sides are practically parallel. They are Lanceolate when they are long compared to the widtn, are pointed at the outer end and taper towards the stem end, the greatest width coming near the stem. Spatulate leaves are rounded or bluntly-pointed, broadest near the tip and taper gradually to the stem. Leaves are Arrow-shaped if they have a V-shaped appendage on each side of the base; if these appendages are rounded, the leaves are called Auriculate. Other common forms are Heart-shaped, Oblong, Oval and Round.
Leaves are Entire-edged when they are neither toothed nor lobed; they are Toothed when the edges are regularly and angularly notched; they are Scalloped when these teeth are rounded.
When a leaf has rounded projections on its edge, it is said to be Lobed; when these projections are angular, it is said to be Incised. A leaf made up of several smaller ones is Compound.
A leaf is Palmately-compounded or Palmately-lobed when the leaflets, or the lobes, radiate from a common center. A compound leaf is Pinnate when the leaflets are regularly arranged on either side of a common stem or axis; when each of these leaflets is also pinnate, the entire leaf is said to be Bipinnate.
A leaf stem is called its Petiole. Leaves that have no stems, but are seated directly-aipon the plant stem, are said to be Sessile. If the plant stem apparently pierces the leaf, the latter is Perfoliate. Two leaves appearing, one on either side of the stem, at the same height are Opposite. If three or more leaves appear about the stem, at the same height, they are Whorled. Alternate leaves are those appearing regularly along the stems at different heights. If the leaf should clasp the stem with its base it is said to be Sheathing.
Bracts are small leaves that appear oftenest at the junctions of flower stems with the stalk. Stipules are small bracts often appearing where a leaf petiole joins the stem.
A Perfect flower is one that has a pistil and stamens. The Pistil is usually in the center of the blossom; it is composed of the Ovary, containing the seeds, usually located at the base; of a Stigma, for the reception of pollen, usually at the summit of the pistil; and of a Style, this being the, usually, slender connecting link between the sigma and the ovary.
Stamens usually radiate from the base of the pistil. At their ends we find enlargements or little cases called the Anthers; these contain fine, dust-like particles called Pollen.
A simple, regular, perfect flower has a Calyx, the outermost part of the floral envelope, divided into four or five parts each being Sepal, a Corolla, the inner part of the floral envelope, divided into four or five parts called the Petals, a pistil and four or five stamens. This is the most simple form of flower; from it there are endless variations. Some have one of the petals enlarged, dilated, twisted or broadened into some unusual form as shown in the Orchids, others have two or more of the petals united as in the Pulse Family; or again, the sepals and petals may be uniform in size, shape and color as in the Lilies, the whole forming what is called the Perianth.
Reference to the plate of Flower Forms will give one a much clearer idea than would text in regard to the outlines of flower shapes commonly found. A single flower, or flower head, at the end of a simple stem is called Solitary and Terminal. If several are grouped together, they are in a Cluster. Clusters or solitary flowers may occur at the ends of branches or from the angle formed by a leaf and the stem, in which case they are said to be Axillary.
Clusters of flowers assume different forms. When the blossoms are distributed along the upper part of the stem, each on a slender pedicel and at different heights, they are in a Raceme, if they are so distributed, but the flowers are stemless the formation is said to be a Spike. If the cluster is rounded or hemispherical, the flower pedicels all radiating from a common point, it is said to be an Umbel. If the cluster is rather flat on top and the pedicels meet the axis at different points, it is a Corymb. If the end of a stem is enlarged, thick and fleshy, and has tiny flowers grouped on its surface, it is a Spadix. If this spadix is enclosed in a leafy or fleshy protection, the latter is a Spathe.