by a much thinner seeding than is ordinarily practiced. With rye, wheat, oats, barley, buckwheat, etc., the shading effect is at a minimum. Slowly available forms of nitrogen should be avoided unless applied very early. Under this restriction come such as raw bone, leather scrap, hair, etc.; especially is this true if no green manure crop be used. Excessive or late applications of nitrogen in any form favors immaturity.

The strictest application of these principles however will not suffice to entirely prevent winter injury from low temperatures, but if the injury is conditioned upon immaturity of bud and cane tissues, adherence to the practices above outlined will temper considerably the degree of killing.

CULTURE OF THE GLOBE ARTICHOKE.*

J. W. WELLINGTON.

SUMMARY.

The Globe artichoke has been successfully cultivated on the Station grounds for several years.

Altho generally known as Cynara scolymus Linn., this vegetable is really a variation of cardoon, Cynara cardunculus Linn. The horticultural varieties are not clearly defined as is shown by the differences between seedlings of a named sort.

The plant is not fully hardy in our latitude and requires covering to endure the winter. Coal ashes proved to be a satisfactory material with which to cover the artichoke, affording sufficient protection without causing decay of the crowns.

From records taken, it is evident that marked variations exist in the producing capacity of individual plants of a variety.

Consequently the separation of the offshoots from the old main root of the plant is the most reliable method of propagation and should materially assist in the establishment of uniform and meritorious strains.

The edible portion of the artichoke is the flower bud.

The plant itself is remarkably thrifty in growth and is practically free from fungus and insect pests. One insect, a black aphid or louse, becomes troublesome at times but is satisfactorily controlled by spraying with a properly prepared dilution of Black Leaf 40 and whale-oil soap.

GENERAL INFORMATION.

The Globe artichoke (Cynara cardunculus Linn.) is a perennial plant which under favorable environment may produce profitable crops for several years. It has been successfully grown on the Station grounds for several seasons. Special attention has been given to winter protection and to a study of variations within a * Reprint of Bulletin No. 435, May, 1917.

horticultural variety. The Globe artichoke, altho widely distributed in this country, has never become a general favorite among vegetables because of its varying ability to survive our Northern winters and also because of the prejudice against uncommon foods.

BOTANICAL CLASSIFICATION.

Index Kewensis classifies the Globe artichoke as Cynara cardunculus Linn., making it a variation of cardoon and not a distinct species. The commonly used and accepted species designation, Cynara scolymus Linn., is given as a synonym. From observation of the two vegetables as they grew on the Station grounds this past season one readily accepts the supposition that the two are closely related cardoon with spiny leaves and flower buds seeming to be but crude forms of Globe artichoke. At a short distance the two cannot be distinguished. Jerusalem artichoke, Helianthus tuberosus Linn., is a distinct species belonging to another genus of the Compositae family. In the Jerusalem artichoke the edible portion consists of the underground tubers. Because of their common name— artichoke - the two vegetables are often confused in the minds of those who know only one or neither of the two species.

HISTORY.

De Candolle2 believed the artichoke to be derived from the cardoon and, since the latter is indigenous to the sandy shores of the Mediterranean Sea, there must also be the home of the artichoke. Sturtevant came to the conclusion that the artichoke was not utilized as food until the fifteenth century. It is asserted that the artichoke was first introduced into England in 1548.

VARIETIES.

The horticultural variations of the Globe artichoke are not sharply defined, due undoubtedly to the ease with which the flowers are naturally crossed. Hence seedlings do not always come true to type. Vilmorin1 mentions thirteen varieties differing in shape and color of the flower buds and in the presence or absence of spines.

1 Hooker & Jackson. Index Kewensis 1:686. 1895.

2 De Candolle. Orig. Cult. Pls., p. 93. 1885.

3 Sturtevant, E. Lewis. Am. Naturalist, 21:126. 1887.

• Vilmorin. Les Pls. Potag., p. 14. 1883.

However, there are only a very few sorts listed in our American seed catalogs, prominent among which are the Green Globe and the Purple Globe. The lack of distinctive names implies that the varieties have not been carefully standardized.

STATION STUDIES.

In February, 1913, two hundred fifty Green Globe artichoke plants were bought from a Southern firm. One hundred of the best plants were set in the garden in April. About twenty plants fruited that fall and these, together with twenty non-producers, were dug and stored in a cold house. In the spring of 1914 suckers from these old roots were potted and two rows placed in the garden. Ten of the fifty plants bore fruit. In 1915 the two rows yielded an abundant crop, some plants being peculiarly prolific, while others bore very few edible buds. These variations suggested taking careful records. During the first two or three years it was discovered that the artichoke not only needs winter protection but that it is particular in its requirements. A non-heating material coal ashes-proved very — satisfactory.

In the season of 1916 the plants of the two rows were given individual numbers and records kept of their performance. Table I shows at once the great variations that exist in the yielding capacity of different plants. The season was, however, peculiarly unfavorable to the artichoke, a crop which requires ample moisture during its fruiting season. The records do not, therefore, give a fair interpretation of the Globe artichoke's value. In normal seasons the yield is not only greater but also extends over a much greater period. Plate LXIII gives a view of the plants as grown at the

Station.

CULTURE.

The Globe artichoke may be easily grown from seed either by starting the plants in a frame under glass or sowing the seed directly in the open ground. The seeds are large and germinate quickly, consequently young plants are easily grown. A pan of seedlings of the Green Globe variety is shown in Fig. 24. The objection to the seedage method of propagation is that it produces a great number of strains, similar in external appearance but differing in productivity. Propagation by means of suckers is the more satisfactory method of