Heliotropium
(old Greek name used by Theophrastus, from helios, the sun, and trope, a turning; according to the ancients, it turned with the sun). Heliotrope; Turnsole. ORD. Boragineae. A large genus (about 150 species have been described, although, in all probability, not more than 100 are entitled to specific rank) of ornamental, strigose, greenhouse or hardy annual herbs or sub-shrubs, rarely shrubs, widely dispersed throughout the tropical and sub-tropical regions, with eight species reaching to Europe. Flowers blue or white, small, in circinate, secund spikes; corolla salvershaped. Leaves alternate, rarely sub-opposite. H. peruvianum and its varieties are amongst the most popular of cultivated plants, on account of the fragrant smell emitted by their flowers. The plants do not require any great amount of heat, but none are more quickly injured by cold, especially when this reaches the freezing point. They may be grown as dwarf decorative subjects, in small pots, or treated as large pyramid and standard specimens. Some of the varieties are very dwarf, and are useful for summer bedding. Old specimens of taller-growing ones are frequently found trained on the back wall of a warm greenhouse. Cultivation. Heliotropiums, or Heliotropes, as they are more popularly called, may be readily increased from seeds or cuttings; the latter method being adopted with named varieties. Young growing points make the best cuttings; and early spring, or the month of August, is a good time for inserting them. If old plants are grown in heat, cuttings from them root quickly in a close frame, and their points may afterwards be used for increasing stock in preference to others not growing so vigorously. The young plants should be potted off singly, and grown on in a temperature of about 60deg., repotting in larger sizes as becomes requisite, and according to the shape or size of plant required. Cuttings intended for standards should be inserted in the autumn, and kept growing all the winter, with a single stem, until they reach the desired height, when the points may be stopped, and the side branches will soon form a head. Old plants may be grown as standards several years in comparatively small pots, by reducing and potting up again in new soil each year. The heads may be trained on trellises, or the branches merely tied in to each other. Large pyramids can be grown in one year by an autumn insertion of cuttings, and due attention. They should be transferred to the full-sized pots as soon as possible, in proportion to their growth, and each trained to a pyramid trellis of any ordinary size. Small decorative plants may be grown to flower in 5in. or 6in. pots, by keeping them pinched when young. Cuttings of varieties used for bedding, should be taken about the middle of August, inserted rather thickly in pots or pans, and placed in a close frame. These should be kept as a stock for spring propagating, and may then be thrown away, as young plants are preferable. Being extremely tender, none should be planted out until June, when the bedding season is nearly over. Standards or others, intended for winter flowering, are best placed outside in a warm position, in summer, to thoroughly ripen them. They should be housed by September, and kept in a temperature of about 55deg. in winter.
H. convolvulaceum (Convolvulus-flowered)* fl. white, sweet-scented, opening at night, generally opposite the leaves and terminal, short-peduncled; corolla limb ample, angulate-lobed. Summer. l. lanceolate, or sometimes nearly ovate, and sometimes linear, short-petioled. h. 2ft. New Mexico, 1867. An extremely showy hardy annual plant. (B. M. 5615.) H. corymbosum (corymbose).* fl. lilac; spikes terminal, aggregate, corymbose; sepals long, subulate. May to September. l. oblong-lanceolate. h. 4ft. Peru, 1808. Greenhouse shrub. (B. M. 1609.)
H. curassavicum (curacoa). fl., corolla limb ample, five-lobed; throat white, with a yellow eye, open; spikes mostly in pairs or twice-forked, densely flowered. June and July. l. linear-lanceolate, glaucous, smooth, opposite and alternate. h. 9in. West Indies, 1731. Stove sub-shrub. (B. M. 2669.)
H. indicum (Indian).* fl. bluish; spikes mostly single, dense-flowered, becoming 9in. to 1ft. long. June to August. l. ovate or oval, rather cordate, on margined petioles, obscurely serrate or undulate. h. 1ft. West Indies, 1713. Stove annual. (B. M. 1837.)
H. luteum (yellow). fl. green, yellow, hypocrateriform. June to October. l. stalked. Stem shrubby. h. 6ft. North Africa, &c., 1779. Greenhouse. (B. R. 464, under name of Tournefortia fruticosa.)
H. peruvianum (Peruvian).* Common Heliotrope; Cherry Pie. fl. very fragrant; spikes terminal, branched, by threes and fours, rarely compound. l. petiolate, oblong-lanceolate, wrinkled, repand, hairy. Stem shrubby. Peru, 1757. Greenhouse. (B. M. 141.)
H. Voltaireanum (Voltaire's). fl. violet. A fine dwarf-growing hybrid. Greenhouse.
Varieties. Of the numerous varieties in cultivation, the subjoined list is a good selection, most of them being of continental origin. For reference and selection, the list is further divided into classes, according to the colour of the flowers and foliage. Those marked with an asterisk are recommended either for their general floriferous habit or for their highly-perfumed flowers.
ADELE, flowers dark lilac, trusses very large; leaves light green, rough; vigorous, free-flowering habit. BOUQUET PERFUME, flowers dark, trusses medium size; very dwarf floriferous habit; an excellent variety. BUFFON, flowers pale lilac, trusses medium size; tall free-growing habit. FLEUR D'ETE, flowers lilac, trusses medium; foliage dark green; rather shy-flowering. MADAME BARBEY, flowers pale-coloured, trusses small; foliage pale green. MADAME DE BLOUAY, flowers pale lilac, trusses large; foliage pale green. MADAME E. SCHILLER, flowers dark-coloured, trusses small; leaves long, narrow. MADAME JUBBINGER, flowers and leaves very dark; floriferous habit; good. MADAME M. KOPFF, flowers whitish-lilac, trusses medium; leaves rough. MADAME P. ATHLES, flowers dark-coloured, trusses large, very freely produced; foliage very dark; good. MISS NIGHTINGALE, flowers dark lilac; dwarf floriferous habit; one of the best for bedding. M. VILGRAIN, flowers pale lilac, trusses immense; very free. ROSE CLAIR, flowers dark, trusses rather small but very plentiful; foliage intensely dark. WHITE LADY, flowers whitish-lilac, becoming nearly white under glass, trusses very large, free; fine variety for winter flowering.
Class I. Foliage and Flowers dark-coloured. *MADAME JUBBINGER, *MISS NIGHTINGALE, *ROSE CLAIR.
Class II. Foliage and Flowers pale-coloured. *BUFFON, MADAME BARBEY, MADAME DE BLOUAY, MADAME M. KOPFF, *M. VILGRAIN, *WHITE LADY.
Class III. Foliage green, Flowers dark-coloured. *ADELE, *BOUQUET PERFUME, FLEUR D'ETE, MADAME E. SCHILLER, *MADAME P. ATHLES.