The Flower Plants In Floriculture

Tabulate or diagram the foregoing data in a floral plan. Note that in this plan in Fig. 5 the relation of point of attachment of sepals, petals, and stamens is indicated whether they be alternate with each other or opposite. This method should be used far more than it is. If done before attempting to use a key, there is less likelihood of making the floral parts fit the specifications of the key, and therefore a more accurate diagnosis is obtained.

The Inflorescence. Just as the individual flower has a definite structure and arrangement of parts, so a cluster of flowers has a pattern, or arrangement, on an axis. This schematic plan of flowers on the stem or axis is termed an inflorescence.

1. Solitary Flowers. Flowers may occur singly in either a terminal or an axillary position, in which cases they are said to be solitary. This is seen in the fruit plants of quince and peach, the former terminal and the latter mdllary. The flower may be borne at the terminus of a stalk arising at the ground in a number of herbaceous plants (as with bulbs and corms). The stalk bearing the flower in this case is termed a scape, although it is really a peduncle as with any solitary flower. Such a case is familiar in the tulip, crocus, and violet. Since the term inflorescence implies more than one flower in a cluster, this case may be considered apart from the other two categories.

2. The Racemose Inflorescence. This is the most common situation in flower clusters and consists of an axis of unlimited growth bearing the oldest flovTers at the base and the younger ones progressively upward to the tip. The arrangement is familiar in such plants as hollyhock, lily-of-the-valley, and snapdragon. There are various modifications of this racemose inflorescence, but the general scheme is the same. The more usual ones are as follows:

a. RACEME. The individual flowers of the main axis oi peduncle have little stems known as pedicels, and they are of equal length. Examples are lily-of-the-valley, snapdragon, gladiolus.

b. SPIKE. A spike is similar to the iaceme except that the flowers are sessile; i.e., the pedicel is absent, as in buddleia. Cominonly, the flowers are numerous, completely covering a portion of the peduncle as in plantain. In some cases they are in whorls with conspicuous intervals between the whorls as in salvia.

c. CATKIN OR AMENT. This is a spike or raceme with a slender rachis bearing many unisexual, apetalous flowers, which falls as a whole when mature. Examples are ornamental amaranthus, birch, willow, alder.

d. UMBEL. This is a short rachis bearing long-pedicellate flowers of about equal length, spreading umbrellalike as in Queen Anne's lace, ivy, cowslip, onion.

e. CORYMB. The main axis is elongated, and the pedicels are of unequal length. The lower ones are longest; and the upper, or central, ones are shortest, resulting in the flowers lying in a plane. As in all racemose types the lowest ones reach anthesis first, and the maturing of the flowers proceeds upward until the last one to open is at the apex or what appears to be the center. Candytuft is an example.

f. SPADIX. This is a spike with a fleshy axis (rachis). It is sometimes surrounded or overarched by a very large bract—the spathe—as in calla lily, Jack-in-the-pulpit, monstera.

g. HEAD OR CAPITULUM. Numerous small flowers without pedicels are crowded together on a very short rachis called a disk. Osage orange, sycamore, sweetgum, and members of the Compositae, including dandelion and chrysanthemum, are examples.

3. The Cymose Inflorescence. At the growing point a flower bud is produced so that no further elongation of the axis can occur. The other flower buds of the cluster are produced below this point and hence are progressively younger from the tip of the axis toward the base. This gives a situation called determinate growth. The solitary flower is, in a sense, cymose. This situation is seen in the begonia, kalanchoe, exacum, hydrangea, viburnum, carnation.