The Cyto-Ecology of Four Species of Trillium from Western North Carolina

Abstract

The major center of variability in the genus Trillium occurs in the southern Appalachian mountains of the eastern United States. The karyotypic variation existing within T. cuneatum Raf., T. grandiflorum (Michx.) Salisb., T. erectum L., and T. gleasoni Fern., the four most abundant Trillium species in western North Carolina, was analyzed and compared with the variation in gross morphology and the ecological associations of the respective species. The number of types of each kind of chromosome (A‐E), as exhibited following “nucleic acid starvation” by cold treatment, varied widely from species to species. Chromosome types varied within each species and within populations in the numbers, sizes, and positions of euchromatic and heterochromatic segments. No 10‐chromosome karyotype and only one 5‐chromosome complement was found to be duplicated in any two plants which belonged to different species. Trillium cuneatum with eight chromosome types was morphologically stable and occurred in a limited geographic area. Trillium gleasoni, characteristically adapted to elevations near 2,000 feet, contained 32 chromosome types and exhibited a high morphological variability. Trillium erectum (25 types) and T. grandiflorum (23 types) were also intermediate in morphological variability. These two species had the widest geographical range. Karyotypes were analyzed from pure stands of each of the four species and for each species from mixed stands of two or more of the species growing in close association. These Trillium species are maintaining a high level of karyotypic and gross morphological variability within comparatively limited geographical areas. None of the observed karyotypes in any species is likely to have arisen by recent interspecific hybridization. The composite karyotype of each species could be used as an aid to classification in the genus Trillium.

Chromosome atlas of the vascular plants of western Pennsylvania. I.

“…The complement is characterized by a long metacentric pair (pair 1), three submetacentric pairs (pairs 2-4), and a short subtelocentric pair , 1954a, 1954Darlington and La Cour, 1940;Darlington and Shaw, 1959;Dyer, 1964;Giles and Wilson, 1956;Serota and Smith, 1967).…”

Cytology of Some Variegated Forms ofTrillium Grandiflorum(Liliaceae)

“…HooPER et al ( 1971) found mycoplasma-like organisms within the phloem cells of such plants and concluded that variegation and associated abnormalities in the species should be regarded as a pathological condition. Extensive studies on the cytology of several species of Trillium have been conducted by various workers (WILSON and BooTHROYD 1944;RUTISHAUSAR 1956;DARLINGTON and SHAW 1959;DYER 1964;SEROTA and SMITH 1967;CHINNAPPA and MoRTON 1978;FuKUDA and GRANT 1980). However, detailed cytology of the aberrant forms of T. grandiflorum has not been investigated.…”