- University of Toronto
Summary
The effect of plant size on reproductive characteristics was examined in a natural population of Erythronium americanum Ker. The number of ovules, fertilized ovules, unfertilized ovules, aborted seeds, and seeds and the fruit weight were found to be correlated positively with plant weight. Only 35% of the available ovules per plant were fertilized and 24% became seeds. Despite the low rate of ovule fertilization, nearly one-third of the fertilized ovules aborted before maturing into seeds. The majority of plant biomass was placed into nonsexual stuctures and, of these, the corm accounted for 60% of the dry weight, leaves 21%, and stem 12%. The remaining 7% was allocated to sexual structures.
Methodology
Erythronium americanum Ker. is a common spring ephemeral of eastern North American deciduous forests (Gleason and Cronquist 1963). Populations contain single-leaved immature plants and double-leaved fertile ones. The species is iteroparous but individuals usually do not reproduce sexually until after 5 years of vegetative growth (Holland 1974). Sexually mature plants produce a single, yellow, hermaphrodite flower which is self-incompatible (Bernhardt 1977). The study site was a beech-maple woodland near the Queen's University Biological Station in Leeds County, Ontario. The dominant associated herbaceous species in flower at the time of sampling were Trillium grandiflorum (Michx.) Salisb., Dicentra cucullaria (L.) Bernh., Aquilegia canadensis L., and Claytonia virginica L. On May 9, 1982, approximately 1 week after the completion of flowering, 25 sexual plants were collected to determine if a relationship existed between leaf weight and total plant weight. This was done so that in future collections whole plants would not have to be removed if leaf weight was a reliable predictor of plant weight. These two characters have been found to be positively correlated in the related Erythronium japonicum (Kawano et al. 1982). Sampling was performed by removing the first 25 plants encountered along a transect through the population. Roots and rhizomes were eliminated from the collection because they were not all removed but the corm which occurs at a depth of about 15 cm was included. Therefore, in this study plant weight includes corm, leaves (two), stem, fruit, and fruit contents. These plant parts were oven-dried at 90°C for 4 days and weighed.