BUSS, CRAIG C., THOMAS G. LAMMERS*, AND ROBERT R. WISE. Department of Biology and Microbiology, University of Wisconsin Oshkosh, Oshkosh, WI 54901. - Systematic implications of seed coat morphology in Cyanea and allied genera of Lobelioideae (Campanulaceae).
Recent surveys of seed morphology in Lobelioideae (Campanulaceae) by
Murata (1992, 1995) have led to a taxonomic revision of Lobelia
L. and demonstrated the utility of such data in understanding
systematic relationships within the subfamily. We have examined via
scanning electron microscopy 52 additional seed accessions,
emphasizing genera in which no species or only one species was
examined by Murata. Foremost among these was the Hawaiian endemic
Cyanea Gaudich., which comprises 75 species, only one of which
(C. kunthiana Hillebr.) was examined by Murata. We examined 25
accessions, representing all major clades in the published phylogeny
of the genus inferred from chloroplast DNA (cpDNA) restriction site
analysis. Most were characterized by Type C morphology (the type
reported by Murata for C. kunthiana), including species
formerly segregated as Rollandia Gaudich., thus supporting
synonymization of that genus. However, the species comprising the
C. angustifolia-clade [sect. Delisseoideae (Hillebr.)
Rock, s. str.] within the "Purple-fruited Clade" have
a unique seed type with prominent bump-like lignose thickenings on the
testa, thus offering a morphological marker for this
molecularly-defined clade. We also examined seeds of the related
Hawaiian endemics Brighamia H. Mann (both species) and
Delissea Gaudich. (2 of 10 species) and found a second testal
pattern (characterized by prominent transverse ridges) not reported by
Murata. This supports the sister-status of these genera, a
relationship originally revealed in the cpDNA phylogeny. The pattern
observed in the C. angustifolia-clade appears to be
intermediate between the Brighamia-Delissea pattern and
Murata's Type C, supporting earlier hypotheses that C.
angustifolia and its relatives lie nearest the ancestry of the
genus.
Key words: Campanulaceae, Cyanea, Lobelioideae, scanning electron microscopy, seed morphology