Pc. Marino et al., INFLUENCE OF SUNLIGHT AND SOIL NUTRIENTS ON CLONAL GROWTH AND SEXUAL REPRODUCTION OF THE UNDERSTORY PERENNIAL HERB SANGUINARIA-CANADENSIS L, Journal of the torrey botanical society, 124(3), 1997, pp. 219-227
Sanguinaria canadensis L. is a rhizomatous understory perennial herb t
hat varies considerably in clone size, leaf size and allocation to sex
ual reproduction among local populations. Permanent plots were establi
shed in a high-light site with large, many-leafed plants and a low-lig
ht site with small, few-leafed plants. Within these plots, a reciproca
l transplant study was performed to separate local evolutionary differ
entiation from environmentally determined differentiation. Also, half
the plots in each site were fertilized to explore effects of soil fert
ility on vegetative growth and sexual reproduction. Plants from a thir
d high-light site were used in a potting study to explore combined inf
luences of elevated sunlight and fertilization on vegetative growth an
d sexual reproduction. Fertilization resulted in plants with proportio
nally fewer small and more large leaves in high-light permanent plots
and had no effect on plants growing in low-light permanent plots. Fert
ilization increased leaf number and total leaf area, but had no influe
nce on seed production in the potting and reciprocal transplant studie
s. Unshaded plants had significantly more leaves and greater total lea
f area in the potting study. Also, in the high-light site of the recip
rocal transplant study, both fertilized and unfertilized plants (espec
ially fertilized plants originating from the high-light site) had more
leaves and a higher total leaf area per plant than plants growing in
the low-light site. Light intensity did not influence seed production
in the potting study; however, more seeds were produced on plants grow
ing in the high-light site than in the low-light site. Mortality was h
igh for plants transplanted into the low-light site and for fertilized
plants growing in shade in the common garden study. Clonal growth as
measured by leaf size and leaf number in S. canadensis is highly plast
ic and responds vigorously to increased sunlight and to fertilization
when under high-light conditions. In contrast, sexual reproduction exh
ibits relatively little plasticity. We suggest that local populations
of S. canadensis rapidly respond to increases in light and nutrients a
ssociated with disturbance through increased clonal growth. This rapid
response to environmental variability may partly explain the patchy s
patial distribution of S. canadensis populations.