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Sunflower: Helianthus. Since the publication of Volume III some progress has been made in the study and breeding of sunflowers, and a brief account of the principal results follows: The investigations of A. H. Church, of Oxford, have shown that the typical unbranched monocephalous sunflower (Helianthus annuus, Linn.), which is not known in the wild state, has come down to us unchanged from ancient times, and existed in cultivation in pre-Columbian America. It was grown at Madrid and described by Dodonaeus as early as 1567. (American Naturalist, XLIX (1915), page 609). It is found that "marking factors" exist in rays of annual sunflowers, which give rise to different patterns when the anthocyan colors are introduced. The system of markings in H. annuus and varieties is quite different from that in H. cucumerifolius (or H. debilis var.) and varieties; thus the red varieties of H. cucumerifolius produced by Herb, of Naples, have rays reddened at the end, or have a red stripe down the middle of the ray, or may have the whole upper surface of ray deep brownish pink, and the under side entirely clear light sulfur-yellow. (Journal of Heredity, VI (1915), page 542). In a culture of red sunflowers (H. annuus, variety) at Boulder, Colorado, a collarette form has been obtained in some numbers, both in the chestnut and wine-red colors. The ray-florets have extra lobes, which are small and directed inward, the structure being like that of the collarette dahlia, though less regular. The type will doubtless be improved in course of time. (Gardeners' Chronicle, November 6, 1915, page 295.) Varieties are now obtained, but have not yet been sufficiently selected and isolated, with two or more rows of rays, in the manner of the star dahlias. It is hoped that some very good forms of the red sunflower will be developed along these lines. A new form of the wine-red sunflower has the bicolor pattern, with the background pale (dilute) orange instead of primrose. This gives, in certain cases, an exceedingly rich and bright color. By crossing the silky-haired H. argophyllus with vinous H. annuus, and again crossing the resulting plants with vinous H. annuus, a very pretty new hybrid has been obtained, the rays very pale yellow, tinted with vinous or with a broad ring of color at the base. It has the H. argophyllus foliage.
As early as 1896 (Bulletin Torrey Botanical Club, vol. 23, page 357) hybrids between annual and perennial sunflowers were recorded, but without details. The hybrid H. annuus x H. scaberrimus (rigidus) was listed by Thellung in 1913. In 1913 Leonard Sutton in England used the pollen of H. rigidus (H. scaberrimus) on the red variety of H. annuus, and obtained fertile seed. The F1 had the characters of the perennial parent, but Sutton reports that an F2 plant has been obtained with small streaks and splashes of red. In 1914 Mrs. Cockerell used the pollen of the perennial H. pumilus on vinous H. annuus, and obtained seeds which produced plants in 1915. These resembled the perennial parent, and formed rosettes only during the first season. An attempt to force these into flower in the greenhouse in the winter of 1915-1916 totally failed; but three seeds of the original lot placed in a coldframe early in 1916 produced plants, one of which is a rosette, while the other two have formed no rosette, and have flowered the first season, like an annual. The largest of the first lot of plants from the H. pumilus x H. annuus cross flowered about the middle of July, 1916, and in its mature form showed a curious combination of characters. The rays, however, were entirely without red, and as is usual with perennials, gave a red color with caustic potash. (Since this was written, one of the hybrids has flowered showing the collarette character, and the lobes forming the collarette are largely red.) This hybrid plant has a curiously close resemblance to the horticultural form known as Daniel Dewar. The broad leaves with well-developed petioles are, however, like those of H. pumilus and H. annuus, not Daniel Dewar. The strongly serrate margins resemble H. annuus. At the present time the hybrids between annual and perennial sunflowers present many problems, and are exceedingly puzzling. It seems probable that results of considerable botanical and horticultural interest will eventually be obtained.
S. Alexander of Michigan has made an elaborate study of the forms of perennial sunflowers growing in his region. He finds that only part of the species are perennial in the strictest sense, the others reproducing by underground branches, having no permanent budding crowns. He also finds that the forms are extremely diverse and has recognized over 600 minor species, differing in a variety of characters. This great diversity of character should afford the basis for many interesting horticultural forms. The nature of these lesser types, from the standpoint of genetics, has not been ascertained. If crossing has taken place, the various combinations arising may have been perpetuated and increased by the system of vegetative reproduction by "earth-branches," which would give us areas covered with plants of the same composition, constituting apparently fixed and constant "species." Alexander finds, however, that the true stationary perennials present a great diversity of forms, though they appear to be far less numerous than are the migrators.
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