Besides the well-known morph with slender branches (f.
capillare Hoffm.), I have noticed additional tendencies of variability in E. sylvaticum
L. (Equisetaceae) in Finland.
1) The ridges of the stem may be smooth, with small papillae
or spines, or rather densely beset with distinct spines. The stem is truly rough
in the last-named case.
2) In southern Finland, deviating plants occur in fairly eutrophic habitats by running
water such as brooksides and spring-places: the ridges of the stem and
consequently the branches of a node are fewer (ca. 8 vs. 8-14), and the sheaths of the first-degree branches are
membranous, translucent, strikingly
silvery white when fresh, becoming clearly brown in drying (vs. appearing slightly thicker
and greenish white when fresh, often paler brown when dry).
3) In central and northern Finland, in many plants that
otherwise are as those of southern Finland, the tips of the teeth of the stem sheaths are black
(vs. brown).
4) In North Finland, at times plants are found that are somewhat glaucous-tinged and possess fewer number of ridges to the stem and consequently
fewer branches at a node (ca. 8 vs. 8-14). Some black colour is present in
the tips of the teeth of the stem sheaths. This kind of plants seem to prefer
rather oligotrophic half-open habitats, being often met with in the transition
zone between forest and a mire or bog.
Created August 30, 2004.