Date of Award

1991

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

First Advisor

Lowell E. Urbatsch

Abstract

Rudbeckia, a North American genus, consists of approximately 21 species of annual and perennial herbs. Rudbeckia is separated into three subgenera (i.e. Laciniata (n = 19 (18)), Macrocline (n = 18) and Rudbeckia (n = 19)) based on morphological, cytological, chemical, and phylogenetic data. The present research includes a systematic study of subgenera Laciniata and Macrocline. Also included is a phylogenetic analysis of the coneflower genera (Dracopis, Echinacea, Ratibida, and Rudbeckia). Subgenus Laciniata contains Rudbeckia laciniata, which is composed of five morphological and geographical overlapping varieties. These include var. ampla, var. bipinnata, var. digitata, var. heterophylla, and var. laciniata. Twelve species are included in subg. Macrocline. Based on the morphometric and cladistic analysis, subg. Macrocline is divided into two sections. The first is sect. Askomia, which contains the rayless coneflowers (R. alpicola, R. montana, and R. occidentalis). The second is sect. Macrocline which comprises the remaining species (R. auriculata, R. californica, R. glaucescens, R. klamathensis (nom. nov.), R. maxima, R. mohrii, R. nitida, R. scabrifolia, and R. texana). The phylogenetic analysis of the coneflower genera places Echinacea within the Rudbeckiinae instead of the Ecliptinae. The genera of coneflowers show a close affinity to each other, and the most primitive taxon is still in question.

Pages

280

DOI

10.31390/gradschool_disstheses.5112

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