Walter H. Lewis

Cytocatalytic evolution in plants

Low fertility and vigor, and requirements of ecological niches distinct from diploids are not universal characteristics of autoploids. InClaytonia, Hedyotis, Oldenlandia, and other genera, occurrence and frequency of both polyploids and aneuploids within species populations suggest a greater role of such mutations in the evolution of vascular plants than heretofore presumed.

Revision of Richardia (Rubiaceae)

A systematic treatment is given for the known species ofRichardia L. with keys, synonymies, descriptions, photographs, typifications, and range maps and/or citations of specimens. The 15 species ofRichardia are grouped into two sections: sect.Richardia with four species from the southern United States to Peru, Argentina, and Brazil; and sect.Asterophyton (K. Schum.) Lewis & Oliver with 11 species having disjunct distributions in three areas: Texas-Mexico, Cuba, and central South America. New combinations areR. tricocca subsp.tetracocca (Mart. & Gal.) Lewis & Oliver,R. muricata subsp.pectidifolia (Urban) Lewis & Oliver,R. arenicola (Britton & Wilson) Lewis & Oliver, andR. ciliata (Britton & Wilson) Lewis & Oliver. Two new species are described:R. boliviensis Lewis & Oliver andR. schumannii Lewis & Oliver.

Pollen differences between Stylisma and Bonamia (Convolvulaceae)

Although discounted in a monograph recognizingStylisma as distinct fromBonamia, pollen morphology is useful in distinguishing these genera, Light and scanning electron microscopy show that the pollen ofStylisma is characterized by an advanced 3-aggrecolpate aperture totaling 12 or 15 colpi, while pollen ofBonamia is typically of a primitive 3-colpate type.

Identifications and Typifications of Rosa (Rosaceae) Taxa in North America Described or Used by E. W. Erlanson, 1925–1934

Abstract.u2003 During her main publication period at the University of Michigan from 1926 to 1937, E. W. Erlanson described 18 new Rosa L. species and varieties (Rosaceae), most from the midwestern United States. The majority were grown and hybridized at the University of Michigan Botanical Garden, where she collected many specimens for the University of Michigan Herbarium (MICH) over a period of years. Some living collections were hers, but most were from others who sent living plants usually without voucher specimens. For this reason and the inability until recently to use sheets as types from living collections under specific circumstances, type selections were at times inappropriate. Nevertheless, seven (almost half) of the cited holotypes here are in MICH, in addition to three lectotypes designated here, as well as isotypes and isolectotypes. A total of 40 taxa with either type data or in synonymy are identified in 10 categories of Rosa species, subspecies, and nothospecies following the Flora of North America treatment. Lectotypes are designated here for the following 19 names: R. acicularioides Schuette, R. acicularis Lindl. var. bourgeauiana Crép., R. arkansana Porter, R. blanda Aiton fo. carpohispida Schuette, R. blanda var. glandulosa Schuette, R. blanda var. hermannii Erlanson, R. blanda var. nuda Schuette, R. blanda var. subgeminata Schuette, R. californica Cham. & Schltdl., R. carolina L. var. aculeata (Schuette) Erlanson, R. carolina var. litoralis Erlanson, R. deamii Erlanson, R. gemella Willd., R. nitida Willd., R. carolina var. inermis Schuette, R. carolina var. sepalorelevata Schuette, R. pensylvanica Michx., R. ×rudiuscula (Greene) Erlanson, and R. suffulta Greene var. valida Erlanson. One neotype is designated, R. palustris. In addition, holotypes of the following taxa are identified for the first time: R. blanda var. setigera Crép., R. blanda var. hispida Farw., and R. blanda fo. alba (Schuette ex Erlanson) Fernald.

A new species of Byrsonima (Malpighiaceae) from Panama

Byrsonima dressleri is newly described as endemic to the low cloud forests of Panama adjacent to the Canal Zone. Its closest relationship appears to be with those taxa of the Guayana Highland and Amazonia.

Hedyotis correllii (Rubiaceae): A new Texas species

Hedyotis correllii is newly described as endemic to the Rio Grande Plains of southern Texas. It is closely allied toH. humifusa by gross and micromorphological characters.