Persicaria lapathifolia (L.) Gray ssp.
lapathifolia (on the left) and P. lapathifolia ssp. pallida
(With.) S.Ekman & T.Knutsson (on the right) (Finland, Tuusula, Halosenniemi,
2001).
– Image: Harri
Harmaja (scanned from dried specimens).
– The type
subspecies has swollen stems at the nodes, rather slender spikes, a reddish perianth,
small perianth and nuts, and the shape of the nuts is narrowish. In ssp.
pallida, the stem is hardly swollen, the spikes are thicker and often more
erect, the perianth is whitish, the perianth and the nuts are larger, and the
nut is relatively broader in shape. The taxa may also differ in the indumentum of the
petiole and the in the details of the glands. The latter taxon is often
mentioned to possess darker nuts; in the present case, however, both taxa had
medium brown nuts. In this locality the subspecies were easy to
separate through the above features; they grew side by side in human-influenced, half-open
vegetation on the shore of lake Tuusulanjärvi. At least here, the taxa may not
be indigenous.
P. lapathifolia (Polygonum lapathifolium;
Polygonaceae) is well-known to be a very variable spices, and the
nomenclature of the intraspecific taxa has also been somewhat controversial. The
best solution is probably to treat the species as comprising two subspecies as
presented above. The demarcation between the subspecies is
often indistinct. Moreover, ssp. pallida not rarely possesses tomentose
hairiness to the stem and leaves.
Created August 6, 2004.