Description. Kotukov’s foxglove is a new hybrid species of foxglove, a well-developed perennial herbaceous plant with a height of 50100 cm in Kyiv and 4080 cm in Leningrad. Stems erect, branched, covered with hairs. Basal leaves are large, 1530 long and 815 cm wide, oblong, ovate, with reticulate venation and coarsely serrated edges, felted below, elongated into a wide petiole at the base. Stem leaves partially amplexicaul, 320 long, 615 cm wide. Inflorescence unilateral loose raceme. The flower corolla is pink with a yellowish tint, with dotted spots on the inner plane of the lower lip (Ivanina, 1955; Katukov, 1953, etc.).
\rInterspecific hybridization in the foxglove genus (Digitalis L.).
\rTo obtain a winter-hardy form of foxglove, many interspecific crossings were carried out both in the Soviet Union and abroad (Monteverde, Orlovskaya, Buxton a. Darlington, 1931, Buxton a. Dark, 1934, Swirlowsky, 1939). However, these crossings did not give positive results. Only in 1926, M. A. Kasaeva in KAS received a prolific interspecific amphidiploid hybrid from crossing foxglove 1 purple and large-flowered (D. purpurea L.XD. grandiflora Mil 1.),. which in 1938 we called a pink hybrid (Kotukov, 1953).
\rAt the same time, in the garden of Mertonensis (England), from the same combination, Bexton and his co-workers received a prolific interspecific hybrid, which was named digitalis Mertonensis (Digitalis Mertonensis B them. and D and 1.) (Buxton a. Darlington, 1931; Buxton a. Dark, 1934).
\rAfter receiving the hybrid at CAS, work with it was discontinued. Subsequently, at the Institute of Botany of the Academy of Sciences of the Ukrainian SSR, we managed to restore the pink hybrid by selecting purple foxglove from a mixed crop along with the hybrid. Later, this hybrid was named Kotukov’s foxglove by L.I. Ivanina (Ivanina, 1955).
\rThis hybrid is more winter hardy than purple foxglove, but is somewhat inferior in this respect to large foxglove.
\rResearch conducted by employees of the All-Union Scientific Research Chemical-Pharmaceutical Institute named after. S. Ordzhonikidze on frogs showed that Kotukov’s foxglove does not have a cumulative effect. This was also confirmed by the work of Leningrad researchers (Kovalenko, 1954).
\rA cytological test found that Kotukov’s foxglove has a double set of chromosomes, that is, it is an amphidiploid (two-ploid) hybrid (Oksiyuk, 1939).
\rIn 1948, at the October Hospital in Kyiv, doctor A. V. Krotkoe, at our request, conducted a clinical trial of an infusion of leaves
\rKotukov’s digitalis on sick people. Preliminary data obtained on ten patients gave good results.
\rBased on long-term observations, it has been established that this foxglove has a number of new morphological features and biological features: increased winter hardiness, growth duration in one place (five years), growth power, higher yield, larger leaves and flowers; in addition, it produces seeds in the very first year of sowing and does not have a cumulative effect (Kotukov, 1953).
\rAs a result of multiple crossings of woolly foxglove (Digitalis lanata Еhгh.) and purple foxglove (D. purpurea L.), which we produced between these very distant species, a hybrid was obtained that differed from both parental species in most of the characteristics. The plant had especially beautiful yellow-pink flowers with a brown tint on the outside and a yellow corolla (Kotukov, 1939).
\rRepeated crossings confirmed the possibility of obtaining interspecific hybrids from this combination. In 1949, V.N. Kovalenko also obtained a prolific hybrid from crossing large-flowered and woolly foxglove (D. grandiflora Mi 1 1. X O. lanata Ehrh.), which, according to morphological characteristics, occupied an intermediate position and did not possess cumulative properties.
\rIn order to obtain new interspecific digitalis hybrids with new valuable properties, we carried out both repeated between the original species and saturating crosses with Kotukov’s hybrid digitalis. Hybrids were obtained that differed sharply from the original species. So, if the average number of stem leaves in digitalis purple was 22.5, and in the hybrid digitalis Kotukov 30.2, then in new hybrids from saturating crossing their number was: from the combination digitalis purple X digitalis large-flowered) X digitalis red) 52.0 , and in hybrids (red digitalis X large-flowered digitalis) X large-flowered digitalis) 84.0. The number of basal leaves in the same hybrids was 26, 27, 79, 58, respectively. Consequently, the number of leaves in some hybrids from saturating crosses was two to three times greater,
\rInteresting data were obtained on the size of the leaves and on some other features. Interspecific hybrids obtained from saturating crosses far exceeded the original species in length, leaf width and originality of shape; among them, hybrids from the combination (foxglove purple X foxglove large-flowered) X foxglove purple) were especially distinguished). Most of the interspecific hybrids had petiolate basal leaves, and only one combination had petiolate leaves. Interesting data were also obtained by saturating crossing from the combination (purple foxglove X large-flowered foxglove) X large-flowered foxglove). The basal leaves of hybrids from this combination turned out to be petiolate, and the leaf blades were elongated, of a rather original shape, gradually turning into a petiole; in length, they even exceeded the leaves of purple foxglove (by 57 cm).
\rMost of the new interspecific hybrids obtained as a result of foxglove pollination with purple foxglove pollen, the leaves were much larger. Most interspecific hybrids had petioleless basal leaves, and only one combination gave hybrids with basal petiole leaves (the length of their petioles significantly exceeded the length of the petiole of basal leaves in foxglove purple).
\rThe resulting interspecific hybrids have much heavier leaves. Individual hybrids exceeded even purple foxglove by five to ten times or more in leaf weight, which indicates the likelihood of a significant increase in foxglove yield.
\rEven these far from complete experimental data point to the prospects of work on interspecific hybridization in the foxglove genus.