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Ruellia tuberosais a wide‐ranging tropical, perennial herb that has been designated the type species for the large genus Ruellia.To clarify interspecific relationships, the R. tuberosaspecies complex, including R. nudiflora, R. malacosperma, and R. lorentziana, and R. tuberosa, has been proposed as the redefined and restricted genus Ruellia.All other Ruelliaspecies would be transferred to segregate genera. Biosystematic investigations that included artificial hybridization experiments, herbarium comparisons, chromatographic analyses, and cytological studies demonstrated that R. tuberosais genetically related to a number of North American temperate taxa and to certain other tropical species. The narrow definition of Ruelliacannot be supported from the biosystematic evidence at hand. Morphological comparisons suggest that R. tuberosamay be a primitive component in a broadened generic concept.

The taxonomically complex eastern U. S. species R. caroliniensisproduces six functional or partially functional floral morphs. They are chasmogenes, reduced chasmogenes, morphologic protogynous chasmogenes, multistylous chasmogenes, cleistogenes, and semi‐cleistogenes. The plants are uniformly self‐compatible and generally produce normal fruits and seeds. The species has the morphological basis of a nearly balanced breeding system between allogamous and autogamous reproduction. Observations and comparisons on garden and greenhouse cultures suggest that R. caroliniensisis a seasonal cleistogamic species, and it is proposed that the different breeding systems are the chief causes of the difficult taxonomic problem in the species.

Observations were made on the morphology, seed fertility, pollen viability and meiotic configurations of 22 different interspecific hybrids of 12 North American taxa representative of 3 sections of Ruellia.The hybrids were classified as (1) fully vigorous and fertile; (2) vigorous but with reduced fertility; (3) reduced vigor and fertility; (4) weak and sterile. Hybrids showed meiotic irregularities in microsporogenesis: univalents, chains, precocious separation of bivalents, nondisjunction, and micronuclei were commonly observed. Interspecific pollinations within sect. Dipteracanthusresulted in fertile or partially sterile F1hybrids. Intersectional crosses produced partially or completely sterile hybrids or failed. Assuming that crossability is correlated with degree of evolutionary relationship, the parental species are interpreted in genecological terms to be grouped in polytypic ecospecies. Hybridization experiments doubtless would be of value in clarifying relationships in tropical and subtropical species of Ruellia.

Relationships of the putative Ruelliaspecies, R. caroliniensis, R. ciliosa, R. heteromorpha,and R. succulentawere analyzed by population sampling, investigation of chromosome numbers, garden transplants, and hybridization experiments. Character data from 25 local, Florida populations and from transplants were evaluated. Some interfertility of these “taxa” was demonstrated, as was some interfertility with other species occurring in the eastern United States. Chromosome numbers are n= 17 and 2n= 34. The effect of different breeding systems on population structure is discussed. Total evidence suggests that the 4 “taxa” in question be considered ecological races of a single species widespread in the eastern United States, namely R. caroliniensis.

Long, RobertW. (Ohio Wesleyan U., Delaware.) Natural and artificial hybrids of Helianthus Maximiliani × H. grosseserratus.Amer. Jour. Bot. 46(10): 687–692. Illus. 1959.—An investigation of the occurrence of natural hybridization in two perennial sunflowers, Helianthus Maximilianiand H. grosseserratus, was begun in 1950. Subsequently, artificial F1, F2, and first and second backcross generations were produced. Fertility and vigor were high in all these plants, but F1plants appeared to excel the others in these characteristics. Observations in the experimental garden were supplemented by examination of chromosomes in pollen mother cells, comparisons of herbarium collections, and study of wild populations. Evidence pointed to close genetic relationship of the species and to the occurrence of natural hybridization in areas of distributional overlap. In 1957 and 1958, field work in these areas resulted in the scoring of 18 natural populations, 3 of which consisted of both parental species plus putative F1hybrids. Two explanations are offered to account for the seeming absence of introgression. The results support the conclusion that natural hybridization leads to the establishment of F1hybrids and that introgression does not occur to any significant extent. Although both species display a high degree of interfertility, they are distinct morphologically. For this reason, it is advisable to maintain them as separate species.

Long, RobertW. (Ohio Wesleyan U., Delaware.) Biosystematics of two perennial species of Helianthus (Compositae). I. Crossing relationships and transplant studies.Amer. Jour. Bot. 47(9) : 729–735. Illus. 1960.–The objective of this investigation has been to clarify the genetic relationships of H. giganteusand H. grosseserratususing hybridization experiments, transplant studies, and related biosystematic techniques. The species are morphologically related and are common in the southern Great Lakes region. They are homoploid with n= 17. Two groups of ecological races were identified within each species and generally they are all cross‐fertile. Helianthus giganteusand H. grosseserratusshould be termed ecotypes; apparently they are elements of a large diploid complex (ecospecies) composed of at least 4 taxonomic species.