Paul A. Fryxell

Relationships among New World species of Hibiscus section furcaria (Malvaceae)

Seventeen species ofHibiscus sectionFurcaria are native to the New World, of which 12 (one diploid, nine tetraploids, one octoploid and one decaploid) have been studied cytotaxonomically. New chromosome counts (2n=4x=72) are reported forH. cucurbitaceus, H. flagelliformis, H. kitaibelifolius, andH. laxiflorus. Seventeen types of tetraploid interspecific hybrids (seven new to this study) all showed complete meiotic chromosome homology (genome formulaGGPP) and normal floral development. That all hybrids were nevertheless almost completely sterile suggests a cytoplasmic component to the genetic differentiation of the species. The diversification of the tetraploid species in habits, habitats and geographical ranges is considerable, despite their similar genome constitutions. A key to 17 native and four introduced African species is presented.Hibiscus cerradoensis sp. nov. is described.

Gossypium Germplasm conservation augmented by tissue culture techniques for field collecting

Conservation and utilization ofGossypium germplasm for crop improvement depend on field-collecting seed from wild and feral populations. Since the availability of viable seed cannot always be assured during botanical expeditions, a simple tissue culture method was developed to allow the collection of living vegetative material from the field. Field-testing of this culture method in western Mexico resulted in 10% overall shoot formation from six Gossypium species; seed was not available from four of these species. Rooting the cuttings was possible, but more effective rooting procedures need to be developed for general utilization by field botanists, at least with Gossypium. The methodology will probably be broadly applicable to other plant species, particularly those that easily root from cuttings.ResumenLa conservación y utilización de germoplasma deGossypium para el mejoramiento de los cultivos dépende en colecciones de semilla de poblaciones silvestres y semi-silvestres. Porque no es seguro que se puede encontrar semilla en el campo se desarrolló un método simple de cultivo de tejido que permite la colecció n de esquejes en el campo. Pruebas del método en México occidental resultó en 10% de formación de brotes en seis especies de Gossypium; no se encontró semilla para cuatro de las seis especies. Se demonstró que la formación de raices ocurre, pero apenas; enfonces se require un método más eficáz para el uso de botánicos en el campo, por lo menos con Gossypium. La metodología probablemente se puede aplicar ampliamente a otras especies de plantas, especialmente las que facilmente forman raíces de estacas.

The genus hampea(Malvaceae)

The genusHampea Schlecht. is included in the Malvaceae, tribe Gossypieae, rather than in the Bombacaceae where it was originally placed. Discussion includes the morphology, geography (central Mexico to western Colombia), reproductive cycle, utilization and vernacular names, and cytology (n = 13) of the genus. Three species have perfect flowers; the remainder are dioecious. The 16 species (and one variety) that are accepted are divided into three sections, one of which is further subdivided into three series. The following taxa are described as new:H. nutricia, H. mexicana, H. sphaerocarpa, andH. appendiculata var.longicalyx.

Neotropical Segregates from Sida L. (Malvaceae)

Three genera are segregated out ofSida as natural units,viz. Sidastrum E. G. Baker, enlarged from one species to seven,Krapovickasia nom. nov. including four species, andRhynchosida gen. nov. including two species, one described as new from Bolivia,R. kearneyi. Mericarp and calyx morphology are emphasized in delimiting these genera and in defining the residual genusSida, which now assumes a more natural character.

Clarification of the status of Hibiscus (sect. Furcaria) uncinellus (Malvaceae)

Hibiscus uncinellus andH. bifurcatus have been confused in the literature and in the herbarium. The morphological, ecological, and geographic differences between them are presented, and a lectotype is chosen for the former species.Hibiscus uncinellus is virtually confined to Mexico (plus one Guatemalan station), andH. bifurcatus occurs in the West Indies, South America, and Central America, as far north as Honduras.

The genus sidastrum E. G. Baker (Malvaceae): A correction

Examination of a Jacquin type reveals an incorrect interpretation in a recent treatment ofSidastrum and requires the publication of the new combinationSidastrum multiflorum as the correct name for the species previously calledS. acuminatum.

New species and new combinations in Briquetia and Hochreutinera, and a discussion of the Briquetia generic alliance (Malvaceae)

Two new species ofBriquetia,B. sonorae andB. inermis, are described from northern Mexico, and another species that ranges from Mexico to Bolivia is transferred into the genus asB. spicata. The genus (previously known as monotypic, Paraguayan-Brazilian) is thereby enlarged from one species to four, and its geographical and morphological limits are greatly expanded. Also, a Mexican species ofAbutilon is transferred toHochreutinera, asH. amplexifolia, enlarging that genus from one to two species. On the basis of this new information, the limits of the informalBriquetia alliance are reconsidered; it is considered to include onlyBriquetia, Dirhamphis, andBatesimalva.

New species in Cienfuegosia

Cienfuegosia hearnii (from Aden, Arabian peninsula),C. somaliana (from Somalia and Ethiopia),C. ulmifolia (from Argentina and Paraguay), andC. intermedia (from Mexico) are described as new.

Pavonia ecostata (Malvaceae), a new species from Jalisco, Mexico

A new species ofPavonia (P. ecostata) from the Sierra Cacoma is described and illustrated and compared to its closest allies,P. alia andP. pulidoae.

A new species of Hibiscus from the Amazon basin.

A new species, Hibiscus amazonicus, is described from the Amazon Basin. Characters distinguishing the new species from its nearest relatives presented.