Ecology of a forest weed of Newfoundland: vegetative regeneration strategy of Kalmia angustifolia

Abstract

The vegetative regeneration characteristics of Kalmia angustifolia were studied by examining the near ground and below-ground structures of the plant. Three methods of vegetative regeneration were observed in Kalmia: layering, stem-base sprouting, and rhizomatous growth, which make the plant more resilient than other ericaceous plants of similar stature following disturbance. Layering occurred only in tall old Kalmia of undisturbed habitats. Stem-base sprouting and rhizomatous growth were found to be the most common and most effective modes of vegetative regeneration. These methods were common in both disturbed and undisturbed habitats. Three types of rhizome systems, namely primary, secondary, and tertiary rhizomes, were identified and described for the first time in Kalmia. Secondary rhizomes were found to be the most effective organ for vegetative spread of the plant. Some secondary rhizomes may grow more than 1 m in one growing season. A 5-year-old Kalmia may produce, on average, 36 secondary rhizomes with a total length of 750 cm. Secondary rhizomes of Kalmia first grow horizontally, then come aboveground growing vertically and exhibiting apical dominance. Large numbers of dormant vegetative buds (three at each node) and adventitious roots are produced at the rhizome nodes. Transverse sections of current-year rhizome showed many trichomes. The cells of the pith are thick-walled and are characterized by large lysigenous cavities. The anatomy of axillary buds and leaf primordia of the aboveground stems of Kalmia were similar to buds and bud scales of the rhizome. Key words: Kalmia, disturbance, fire, regeneration strategy, rhizome, trichomes.