MAGOIA YIS A SEECIOS b ph C. Mnl 1 Magnolia, one of the most ancient genera among flowering breeding. In contrast, the intra-sectional salicifolia x Kobus trees, now has one of the newest horticultural organizations hybrids appear quite fertile. Among the four United States sponsoring it. Several of the American Magnolia Society's species belonging to section Rytidiospermum and sympatric members are hybridizing among at least a few of the to various degrees, none is known to have crossed with any approximately 90 known species. Some members, myself other American species within its section, though two have included, have been active in collecting Latin American now been outcrossed on virginiana, and one (M. tripetala) species, and selecting among relatively recently introduced shows suspected compatibility on two related Asiatic eastern Asiatic species in the United States. Breeding is also species. In some inter-specific (and inter-sectional) combi- under way in Japan and England. Within each of the two nations, the cross has been successful in only one direction. large subgenera, most current interest is directed toward There are species (M. acuminata, M. denudata) and varieties ornamental trees and shrubs. But several of the larger (M. virginiana var. australis) with very high clonal self- growing species have timber value. We foresee a possibility sterility, contrasted to high self-fertility in clones of related of getting some hybrids useful to forestry as a by-product species or varieties. of the ornamental breeding. In prehistoric times hybridization no doubt played its Magnolias at present are a smaller component of forest part in the evolution of magnolia species as we now know vegetation than the fossil records indicate they were in them. For hexaploids like M. grandiflora and the Asiatic some earlier epochs, starting with the Cretaceous period. Yulania section, the ancestry could have been very com- But they are still widely dispersed. Along with several plex. Most of the ancestors of Theorhodon, the grandiflora related genera (Talauma, Michelia, Liriodendron) that are section, were probably exterminated in the ice ages, or still included in the Magnoliaceae, both subgenera (Mag- pushed far to the south, where we now have species of nolia and Pleurochasma) are found in both America and limited distribution in the warm-temperate highlands from Asia. M. acuminata, if we include cordata as a variety, is the southern Mexico to easternmost Venezuela. What later sole American species of subgenus Pleurochasma, but it has came northward included some species of wider adapta- one Chinese relative, M liliflora, in the same botanical bility, due in part, we can surmise, to mutations, and partly section. In the subgenus Magnolia, there is section Rytidio- to recombinations of chromosomes previously found in spermum, with four species in the U.S., one in Mexico, one separate species. Whatever their history and interrelation- in the Himalayas and another two in Japan and China. ship, both M. Schiedeana, the most widespread Mexican Other sections are restricted to a single hemisphere, with magnolia, and our own M. grandiflora, distributed from more sections, as well as more species, being Asiatic. Texas to North Carolina, now show a 114-chromosome Several factors complicate the hybridization possibilities. count. M. grandiflora can still cross with the 38-chromo- Though the subgenera may be inter-grafted, pollinations some M. virginiana and the 38-chromosome M. guate- across the subgeneric division, up to now, have yielded only malensis, as demonstrated respectively by Oliver M. Free- apomicts of the female parent. Inter-sectional pollinations man and myself. There is evidence, presented further on, have resulted in some apomicts and some true hybrids, part that grandiflora has received part of its great variability in of which are more or less fertile. In both subgenera, there relatively recent times through natural introgression by M. are both diploids and hexaploids. Both acuminata and virginiana australis in the Georgia to Texas region of species liliflora are tetraploid. Known tetraploids in subgenus overlap. Magnolia include Oliver Freeman's hybrids known to be As I write, I am awaiting the first flower opening on one virginiana x grandiflora, plus the grandiflora-like and fertile of a few hybrids combining Asiatic and American ancestry `Charles Dickens' whose unknown ancestry may include (M. denudata, M. liliflora and M. acuminata). My more macro phylla. extensive work, especially in the past decade, has dealt with Among hybrid magnolias, synthetic pentaploids (M. x field studies, selection and breeding among American Soulangiana) and tetraploids (`Freeman') are partially fer- species and hybrids in subgenus Magnolia, including M. tile in some cases, but no fertility has been found in the grandiflora, M. virginiana and a few others. Particularly triploids. Even several diploid level hybrids, such as rapid progress now is underway with forms and intervarietal intersectional crosses involving M. virginiana with other hybrids of Sweet Bay Magnolia, M. virginiana var. virginiana American and Asiatic diploids, and the Asiatic Sieboldii x L. and M. v. var. australis Sarg., and I shall discuss these hypoleuca hybrid, have been highly sterile to further more fully. I was selecting in Magnolia grandiflora in Alabama more lished his M. grandiflora lanceolata. Known also under its than 30 years ago, and have continued with it in Illinois synonym M. g. exoniensis, the 'Exmouth' cultivar of var. since 1950. M. grandiflora, the evergreen North American lanceolata (first flowered by the 1730's in the Devon town species best known around the world, has been called the of that name), has been horticulturally distinctive enough most extensively cultivated of all American flowering trees to persist into current propagation, and has been used in in other countries. Compared to our Cercis canadensis and recent breeding with which I was associated. (Harvey and Cornus florida, it proved better adapted in the climates of Jewel Templeton of Winchester, Tennessee, gave me recip- the warmer parts of Europe. One current cultivar, 'Vic- rocal hybrids between lanceolata and 'Charles Dickens'.) toria', was selected in Canada. It was on Vancouver Island, Like some of my recent selections and others now in clonal Canada's mildest zone. The species is cultivated in Japan, propagation that may have it as an ancestor, lanceolata being hardier than any of the evergreen Asiatic magnolias, shows enough similarity to some controlled hybrids be- and it has even been taken into the tropics of both tween M. virginiana and M. grandiflora to suggest the hemispheres. Actually, in all probability, M. grandiflora has likelihood that it, too, is of hybrid derivation, probably an not become as truly 'naturalized in Europe and Asia as our F2 or later generation from a chance cross of M. virginiana Robinia pseudoacacia, but it is more often planted for australis x M. grandiflora. Besides the varietal differences strictly ornamental purposes, while the black locust is (lanceolate leaves and less widely opening flowers) de- grown more for other reasons, or tolerated where it springs scribed by Aiton, lanceolata (like known hybrids) has up. stipular scars on some of its leaf petioles. This criterion for M. grandiflora now can be grown from cuttings. Some such hybrids has been suggested in correspondence by the clonal forms have been layered since the 1700's in Europe. British Museum's taxonomist, Mr. J. E. Dandy. M. grandi- There have been three different bases of selection from flora and the numerous Latin American species in its these times: (1) hardiness, still important, particularly as section Theorhodon all are supposed to have their petioles one gets north of USDA Plant Hardiness Zone 7; (2) tree attached to the stem free of the stipules. In M. virginiana and foliage characteristics, which show wide variation; and and all other North American species outside Theorhodon, (3) flower size, quality and abundance, also showing wide stipules are adnate to the petioles, leaving scars where they variation. Color of flower varies little, but form and size are detach. unpredictable in unpedigreed seedlings. Generally, there are M. virginiana was one parent of the next hybrid to come nine tepals, but 12 are seen fairly frequently on some trees' to attention, and that hybrid was long thought to be merely flowers, and about twice that number (counting sta- a variant of Sweet Bay. It originated as a chance seedling in minodes) in those of the "doublest" clone I have seen, the Mr. Thompson's nursery at London in 1808. Its publication `Santa Cruz', named at that California town only this as a hybrid, M. x Thompsoniana C. de Vos, with M. September. tripetala the other parent, came late in the nineteenth In some coastal areas the flowering season frequently is century. I have found this hybridization relatively easy to extended to fall, but in Tennessee and northern Alabama repeat in recent years, but only where M. v. var. virginiana and up to southern Illinois, that is seldom true. My father is the seed parent, as it obviously was with Thompson. The and I selected 'Alabama Everblooming' in the early 1930's reciprocal, and crosses of M. v. australis with tripetala either at Cullman, Alabama, where it usually continued flowering have failed to set seeds, or else such seeds as matured gave into September and sometimes later. It has particularly only non-hybrid, apparently apomictic progeny of the seed fragrant flowers. 'Madison' is another "everbloomer," of parent. Now being multiplied for introduction is one of my neater growth habit, selected in the early 1950's from new M. x Thompsoniana clones. Several of these have the Madison, Alabama, and now in commercial propagation good flower quality of the original clone from England, but near Mobile. 'Cairo' from the southernmost Illinois town, seem as hardy as tripetala and the deciduous virginiana in was registered less than 3 years ago and is not yet Urbana where the crossing was done.