Fig. 110.—Types of Calycifloræ (Umbellifloræ). A, inflorescence of wild parsnip, Pastinaca (Umbelliferæ), × ½. B, single flower of the same, × 3. C, a leaf, showing the sheathing base, × ¼. D, a fruit, × 2. E, cross-section of D. F, part of the inflorescence of spikenard, Aralia (Araliaceæ), × 1. G, a single flower of the same, × 3. H, the fruit, × 2. I, cross-section of the H. J, inflorescence of dogwood, Cornus (Corneæ). The cluster of flowers is surrounded by four white bracts (b), × ⅓. K, a single flower of the same, × 2. L, diagram of the flower. M, young fruit of another species (Cornus stolonifera) (red osier), × 2. N, cross-section of M.
The last and highest group of the Choripetalæ, the Calycifloræ, embraces a very large assemblage of familiar plants, divided into eight orders and thirty-two families. With few exceptions, the floral axis grows up around the ovary, carrying the outer floral leaves above it, and the ovary appears at the bottom of a cup around whose edge the other parts of the flower are arranged. Sometimes, as in the fuchsia, the ovary is grown to the base of the cup or tube, and thus looks as if it were outside the flower. Such an ovary is said to be “inferior” in distinction from one that is entirely free from the tube, and thus is evidently within the flower. The latter is the so-called “superior” ovary. The carpels are usually united into a compound pistil, but may be separate, as in the stonecrop ([Fig. 111], E), or strawberry ([Fig. 114], C).
The first order of the Calycifloræ (Umbellifloræ) has the flowers small, and usually arranged in umbels, i.e. several stalked flowers growing from a common point. The ovary is inferior, and there is a nectar-secreting disc between the styles and the stamens. Of the three families, the umbel-worts or Umbelliferæ is the commonest. The flowers are much alike in all ([Fig. 110], A, B), and nearly all have large, compound leaves with broad, sheathing bases. The stems are generally hollow. So great is the uniformity of the flowers and plant, that the fruit ([Fig. 110], D) is generally necessary before the plant can be certainly recognized. This is two-seeded in all, but differs very much in shape and in the development of oil channels, which secrete the peculiar oil that gives the characteristic taste to the fruits of such forms as caraway, coriander, etc. Some of them, like the wild parsnip, poison hemlock, etc., are violent poisons, while others like the carrot are perfectly wholesome.
The wild spikenard (Aralia) ([Fig. 110], F), ginseng, and the true ivy (Hedera) are examples of the Araliaceæ, and the various species of dogwood (Cornus) ([Fig. 110], J–N) represent the dogwood family (Corneæ).
The second order (Saxifraginæ) contains eight families, including a number of common wild and cultivated plants. The true saxifrages are represented by several wild and cultivated species of Saxifraga, the little bishop’s cap or mitre-wort (Mitella) ([Fig. 111], D), and others. The wild hydrangea ([Fig. 111], F) and the showy garden species represent the family Hydrangeæ. In these some of the flowers are large and showy, but with neither stamens nor pistils (neutral), while the small, inconspicuous flowers of the central part of the inflorescence are perfect. In the garden varieties, all of the flowers are changed, by selection, into the showy, neutral ones. The syringa or mock orange (Philadelphus) ([Fig. 111], I), the gooseberry, and currants (Ribes) ([Fig. 111], A), and the stonecrop (Sedum) ([Fig. 111], E) are types of the families Philadelpheæ, Ribesieæ, and Crassulaceæ.
Fig. 111.—Calycifloræ (Saxifraginæ): A, flowers and leaves of wild gooseberry, Ribes (Ribesieæ), × 1. B, vertical section of the flower, × 2. C, diagram of the flower. D, flower of bishop’s-cap, Mitella (Saxifragaceæ), × 3. E, flower of stonecrop, Sedum (Crassulaceæ), × 2. F, flowers and leaves of hydrangea (Hydrangeæ), × ½. n, neutral flower. G, unopened flower, × 2. H, the same, after the petals have fallen away. I, flower of syringa, Philadelphus (Philadelpheæ), × 1. J, diagram of the flower.
The third order (Opuntieæ) has but a single family, the cacti (Cactaceæ). These are strictly American in their distribution, and inhabit especially the dry plains of the southwest, where they reach an extraordinary development. They are nearly or quite leafless, and the fleshy, cylindrical, or flattened stems are usually beset with stout spines. The flowers ([Fig. 112], A) are often very showy, so that many species are cultivated for ornament and are familiar to every one. The beautiful night-blooming cereus, of which there are several species, is one of these. A few species of prickly-pear (Opuntia) occur as far north as New York, but most are confined to the hot, dry plains of the south and southwest.