Part 10

HOREHOUND.

Horehound (Marrubium vulgare) is a hardy perennial herb of the mint family, which occurs as a common weed in many places in the United States, especially on the Pacific coast, where it threatens to become a pest. The leaves and flowering tops find some demand as a crude drug. Their greatest use, however, is in the manufacture of candy, although they are sometimes employed for seasoning.

Horehound grows well in almost any soil and thrives in light, dry soils lacking in fertility. It grows readily from seeds, which are usually sown in drills early in the spring and covered with about an inch of soil. Plants may also be started in coldframes, either from seed or cuttings, and later transplanted to the field. Propagation may also be effected by division of old plants. Plants may stand 6, 12, or 18 inches apart in the row; those which stand close together will have small stems, and hence will yield a crop of finer quality.

The plants are harvested just before flowering and should be cured in the shade in order to preserve the green color. If the stems are small, the plants may be cut close to the ground with a scythe, or with a mower if the area is large. In case the plants are tall and large they must be cut some distance above the ground and all coarse stems removed to make the herb suitable for marketing.

Yields at the rate of 2,000 pounds of dry herb per acre have been obtained. The prewar wholesale prices for the herb ranged from 5 to 8 cents a pound. The price in June, 1920, was 15 to 16 cents. The annual importation of horehound varies from year to year, sometimes reaching 60 to 70 tons.

INSECT-POWDER FLOWERS.

Insect flowers, from which pyrethrum or insect powder is prepared, are produced by several species of plants of the aster family which occur wild in the eastern Mediterranean region, where they are also cultivated.

The species here considered (Chrysanthemum [Pyrethrum] cinerariaefolium) has been cultivated commercially in California for the production of insect powder. This species seems to thrive best in warm situations and should grow well in any good soil which is well drained and not too heavy. The seeds may be sown directly in the field, either early in the spring or in the fall, but it is preferable to start the plants in coldframes or well-prepared seed beds and transplant them to the field. The seed is mixed with sand and sown broadcast on the surface of the bed and lightly covered with a rake. Water should be used sparingly on the seed bed, since the young seedlings and even mature plants are easily killed by a wet soil. When the seedlings are about a month old they are transplanted, during damp weather if possible, and set 8 to 12 inches apart in rows 3 to 4 feet apart. Old plants may also be divided and used for propagation. The plants should be well cultivated during the growing season and will yield flowers for several years if they are well cared for. The fertility of the soil is maintained by the application of fertilizers.

The time of harvesting varies from June to September, according to locality. The flower heads are gathered just as they open and may be collected by hand or by means of a flower picker. They are dried, preferably in the shade, on canvas sheets about 15 feet square, on which they are spread in a thin layer and turned two or three times a day until dry.

The average yield of dried flowers appears to be about 450 pounds per acre. The wholesale price for these flowers in June, 1920, was 85 to 90 cents a pound, which is from three to four times the prewar price.

LARKSPUR.

The larkspur of the crude-drug trade is an annual plant (Delphinium consolida), native of southern Europe, which has long been cultivated in this country as an ornamental and is now occasionally found growing wild. Another species of larkspur (Delphinium urceolatum) is native to this country and is said to have properties very similar to those of the European species. Larkspur seed is now used chiefly in remedies for external parasites.

These larkspurs thrive best in a rich sandy or gravelly soil. In heavy soils they are likely to suffer from root-rot, which materially reduces the yield. A rather dry climate is suitable for plants of this character. They do not bear transplanting well and seeds should be sown in the fall or very early in the spring where the plants are to stand. The soil should be well fined and the seed thinly sown in drills spaced according to the method of cultivation to be used. When up, the plants should be thinned to stand 8 inches or more apart in the rows. The necessary cultivation consists in keeping the soil between the rows and about the plants mellow and free from weeds during the growing season.

When the seed capsules are fairly ripe, the seed is harvested by collecting the tops, which should be cut before the seed capsules have become so brittle as to risk the loss of seed by shattering and which can be handled best in the early morning while damp and pliable. They should be cured in a well-ventilated place, sheltered from rain, and when thoroughly dry may be thrashed out and cleaned.

The wholesale price now quoted for larkspur seed is between 32 and 35 cents a pound.

The seed of a European species of larkspur (Delphinium staphisagria), commonly-called stavesacre, possesses medicinal properties and is recognized as an official drug. The wholesale price for stavesacre seed in June, 1920, was about 30 cents a pound.

LAVENDER.

The true lavender (Lavandula vera) is a small shrubby plant of the mint family, native to southern Europe, and widely cultivated for its fragrant flowers and for the oil distilled from the fresh flowering tops.

Lavender thrives best in light and rather dry soils well supplied with lime, but may be grown in almost any well-drained loam. On low or wet land it is almost certain to winterkill. The plant is not easily grown from seed, but may be readily propagated from cuttings or by division. In cold climates the plants must be well protected during the winter, or they may be carried over in a greenhouse or coldframe. Early in the spring the plants or rooted cuttings are set in well-prepared soil, 12 to 15 inches apart in rows spaced to suit the cultivation intended. Frequent and thorough cultivation is desirable.

Not many blooms can be cut the first year, but full crops may be expected for each of the three following years, after which it will be best to start new plantings. The flowering tops are harvested when they are in full bloom, and if used for the production of oil are distilled at once without drying. If the dry flowers are wanted, the tops are carefully dried in the shade and the flowers later stripped from the stems by hand.

On ordinary soil, yields of 600 to 1,200 pounds per acre of fresh flowering tops have been obtained. The dry weight is about four-fifths of the green weight. The yield of oil varies widely, but from 12 to 15 pounds per acre may be expected under good conditions. The wholesale prices in June, 1920, were about as follows: For "ordinary" flowers, from 18 to 24 cents a pound; for "select" flowers, from 30 to 35 cents a pound; for oil of lavender flowers, $11 to $12 a pound.

LICORICE.

Licorice (Glycyrrhiza glabra) is an Old World plant, the culture of which has not succeeded commercially in this country, although the plant grows well in the arid Southwest and in California, where in some localities it threatens to become a weed. Licorice is used to some extent in medicine, and is said to be much in demand by manufacturers of tobacco.

Licorice is a fairly hardy plant, but it thrives best in warm regions, where the season is sufficiently long to promote strong growth. Plants may be grown from seed, but propagation by means of cuttings made from the younger parts of the Rhizome, or so-called root, usually gives best results. The cuttings are set perpendicularly in deep, moist, sandy, or loamy soil, and should stand about 18 inches apart in rows so spaced as to allow for the cultivation necessary to keep the soil mellow and free from weeds.

The yield under good culture is said to average about 5,000 pounds of dry root per acre at the end of every third year. The relatively low price at which, the imported root can usually be obtained has so far prevented the development of commercial licorice growing in this country. Nearly 100,000,000 pounds of licorice root and an average of about 600,000 pounds of licorice paste are annually imported into the United States when trade conditions are normal.

Prewar prices for the imported root usually ranged from 4 to 5½ cents a pound in bales. The price in June, 1920, was 13 to 14 cents.

LOBELIA.

Lobelia (Lobelia inflata) is a native poisonous annual plant, occurring generally in open woods and pastures, but is most abundant in the States east of the Mississippi River. The leaves, tops, and seeds are used medicinally.