Differences in the location of subcotyledonary buds among Epilobium angustifolium L., E. dodonaei Vill. and E. fleischeri Hochst. (Onagraceae) and effects on architecture and population structure

Abstract

Morphological and architectural features in the two closely related pioneer plant species Epilobium dodonaei and E. fleischeri are examined in cultivation and in the field and compared with E. angustifolium. In E. angustifolium, the aerial shoot system is renewed every year from buds on horizontal roots and results in a horizontal spread and a clonal growth form. In E. dodonaei, bud formation is restricted to the hypocotyl and in larger plants to the transitional region between root and shoot. Consequently this species shows no vegetative mobility and develops a shrub-like habit. The alpine E. fleischeri combines the habit of E. angustifolium and E. dodonaei and may either develop successive generations of shoots from the transitional region between root and shoot and/or exploit new areas by horizontal roots and the formation of shoots from root buds. The simple difference in the location of renewal buds is accentuated by cumulative growth. The study shows that E. dodonaei and E. fleischeri, which often are considered as subspecies, are separated by fundamental differences in their architectural models. The ecological and demographic implications of these differences are discussed.