Scleranthus (Knapwell) is perigynous with bell-shaped torus; no corolla; corolla-stamens are wanting or rudimentary; some calyx-stamens may also be absent.—Corrigiola (Fig. [361] D); Illecebrum; Paronychia (Fig. [361] E); Herniaria (Figs. [361] F, [364]).
3. Sileneæ, Pink or Carnation Group. This has a gamosepalous calyx and unguiculate, white or red, petals, with outgrowths (ligule, corona, paracorolla) at the throat of the corolla. These structures are not found in the other groups, and are merely outgrowths at the junction of the limb and claw. The corolla, stamens and ovary are frequently raised above the calyx, upon a lengthened internode (gynophore). The flower has S5, P5, A5 + 5; fruit a capsule with many seeds.
a. 5-(rarely 3–4) carpellate ovary.—Lychnis (Campion, Fig. [360]). The corolla is longer than the calyx; corona present. The capsule is 10- or 5-toothed, completely 1-chambered or 5-chambered at the base,—the genus has been divided accordingly into several genera: Melandrium, Lychnis, Viscaria. Some species are unisexual by the abortion of stamens or carpels (L. vespertina, diurna). Agrostemma (A. githago, Corn-cockle, Fig. [361] A) has a long-toothed calyx, the teeth exceeding the corolla; corona absent; 5-toothed capsule.
Fig. 364.—Herniaria glabra: a1 flower; b1 longitudinal section through the flower; c1 stigma with two pollen-grains.
b. Tricarpellate.—Silene (Catch-fly). Six-toothed capsule; corona present in the majority.—Cucubalus has berry-like fruits which finally become dry but do not dehisce.
c. Bicarpellate (2 styles, 4-toothed capsule).—Dianthus (Pink); at the base of the calyx 1–several pairs of floral-leaves are situated; corona absent. The straight embryo is a peculiar exception.—Gypsophila has a campanulate, open calyx, 5-nerved, membranous between the nerves; corona absent; the flowers are generally small and numerous, in a large, paniculate dichasia.—Saponaria (Soapwort) has corona.
Pollination. Alsineæ has ordinary nectaries at the base of the calyx-stamens (Fig. [336]): they are frequently protandrous but may often, in the absence of cross-pollination (in the less conspicuous species) pollinate themselves. Their open flowers are accessible to many kinds of insects (particularly flies and bees). Gynodiœcious flowers are found in several species, and the ☿-flowers are then generally more conspicuous than the ♀-flowers. That the ♀-flowers have descended from ☿-flowers is seen by the large staminodes found in them (Fig. [363]). Arenaria peploides is diœcious (Fig. [363]). The Sileneæ are as a rule adapted for pollination by insects with long probosces—especially butterflies,—and they are frequently protandrous, so that at first the calyx-stamens open, later on the corolla-stamens, then the stigmas expand. The honey is secreted by a ring-like nectary round the base of the ovary or by nectaries at the base of the stamens. Some only blossom and emit scent at night or in the evening (Lychnis vespertina, Silene nutans, Saponaria officinalis) and, like other night-flowers, are of a white or pale colour.
Distribution. 1,100 species, especially in temperate climates, fewer in the colder zone, less still in the Tropics. The Paronychieæ are especially found in dry, sandy fields.
Uses. “Soap-root” (with Saponin, forming a lather in water) from Saponaria officinalis was formerly officinal, and Gypsophila struthium. The seeds of Agrostemma githago are said to be poisonous.—The following are ornamental plants: species of Pinks (D. caryophyllus, garden Pink, often with double flowers; D. barbatus, plumarius, etc.). Lychnis, Gypsophila, Silene, Cerastium (C. tomentosum as edging for borders), Saponaria officinalis (often coronate).—Spergula arvensis is sometimes cultivated.