Taxonomic and ecological relationships of Scirpus acutus Muhl. and S. Validus Vahl (Cyperaceae) in southern Manitoba

Abstract

This study was conducted in the period 1970 to 1972 and was designed to examine the taxonomic and ecological relationships between Scirpus acutus Muhl. and s. validus Vahl in southern Manitoba. Taxonomic assessment of the stands was accomplished using the hybrid index based on six characters selected in part from a factor analysis of 13 morphological features. The response of the taxa so defined to a number of environmental parameters was measured using a 'stand performance' index, the product of culm density and fertility. S. acutus and S. validus show morphological discontinuity when six characters are used in combination. S. acutus is characterized by inflorenscences less than 80 mm long; less than 13 primary rays; rare development of secondary rays and absence of tertiary and quaternary rays; spikelets borne in clusters, with at least one cluster of five or more present; and culms dark green to olive green with aerenchymal lacunae less that 1.5 mm, and usually less than 0.86 mm in diameter. S. validus has inflorescences longer than 47 mm, usually longer than 80.5 mm; the number of primary rays usually exceeds 13, but never is less than seven; ray development is extensive with secondary and usually tertiary rays numerous; spikelets are borne singly or in groups of less than five; culms are light green to glaucous with lacunar diameters always greater tha 0.87 mm and usually more than 1.5 mm....