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5. Chamerion Raf. ex Holub
Holub, Folia Geobot. Phytotax. 7: 85 (1972).
Chamaenerion Gray (1821) non Ség. (1754), nom. illeg.
Hemicryptophytes (rhizomatous perennials). Leaves alternate, subsessile. Inflorescence a terminal, simple, bracteate raceme. Flowers zygomorphic, 4-merous. Hypanthium absent. Sepals free at apex, connate at base, spreading. Petals pink to purple or rarely white, entire, the lower ones narrower than the upper ones. Stamens 8, subequal; pollen grains shed singly. Style at first deflexed, later turning upwards; stigma deeply 4-lobed. Capsule narrowly linear, terete to quadrangular, opening with 4 valves. Seeds numerous, almost smooth, with an apical plume of hairs.
Chromosome base-number x=18.
Biology. The flowers are adapted for cross-pollination, with male and female functions separated in space and time (herkogamous and protandrous). At the release of pollen, the style is deflexed, and the stigma unopened, not receptive. Later on, the style straightens and the stigma lobes are exposed, while the stamens bend downwards. The flowers remain open for 3–4 days and are mainly pollinated by bees.
Vegetative propagation takes place by the branched, far-creeping rhizome, and extensive clones are frequently formed. New populations, however, often establish from seed in disturbed spots.
Taxonomy. The genus Chamerion has often been regarded as a section within Epilobium, and the two genera share a unique capsule type, seed with a tuft of hairs, and a chromosome base-number of x=18. Nevertheless it seems most natural to regard it as a separate genus (Wagner et al. 2007). Chamerion is distinct in several features, including alternate leaves, subequal stamens, zygomorphy and lack of hypanthium. Molecular analysis provides strong support for Chamerion and Epilobium as monophyletic groups (Baum et al. 1994).
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Plant mostly tall, inflorescence a usually 20–50-flowered raceme; leaves narrowly lanceolate to linear, with conspicuous veins |
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Plant low (usually at most 40 cm), inflorescence an up to 10(–25)-flowered raceme; leaves lanceolate, with inconspicuous veins |
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1. Chamerion angustifolium (L.) Holub Map
Holub, Folia Geobot. Phytotax. 7: 86 (1972). – Epilobium angustifolium L., Sp. pl.: 347 (1753). – Chamaenerion angustifolium (L.) Scop. (1772). – Type: Linnaean Herbarium 486.1 (LINN) lectotype, sel. by Raven, Notes Roy. Bot. Gard. Edinburgh 24: 186 (1962).
D Gederams. Fa sigurskúvur. F maitohorsma. I sigurskúfur. N geitrams. S mjölke.
Rhizome stout, branching; new shoots sometimes formed also from the roots. Shoots 50–200 cm, erect, usually unbranched, with many spirally arranged leaves. Stem glabrous or subglabrous. Leaves 5–20 × 1–3 cm, narrowly lanceolate, acute, entire, glabrous; petiole 0–3(–5) mm; veins pinnate with strong midvein and inconspicuous side veins.
Inflorescence a simple (or rarely branched) many-flowered raceme; upper bracts gradually smaller; fruiting pedicels 7–20 mm. Buds reflexed. Flowers slightly zygomorphic. Sepals very narrowly ovate to linear, apiculate, pinkish purple. Petals 10–13 mm, obovate, obtuse or slightly emarginate, purplish to reddish pink or rarely white. Stamens with filaments 9–15 mm; anthers 2.5–4 mm. Style 10–20 mm. Stigma deeply 4-lobed. Capsule 40–100 mm, densely eglandular-hairy. Seeds 1.1–1.4 × 03–0.45 mm, smooth at low magnifications; neck dark, c. 0.1 mm; seed hairs 8–12 mm. – Summer to early autumn.
2n= 36 (F KP, N Ak, S Sk 2). [2n=36, 72, 108, natural haploids 18]
Distribution. Nem–LAlp[–MAlp]. Alt. 1780 m ( N Op Lom). – Indigenous in mainland Norden and ± common throughout; much increased through human activities. Fa widespread but rare; Suðuroy, the central islands and Borðoy. I native and fairly common in INo and IAu, elsewhere anthropochorous and fairy rare to rare.
Circumboreal. Tetraploids and hexaploids (not known from Europe) are sometimes segregated as subsp. circumvagum (Mosquin) Hoch.
Habitat. A light-demanding species of dry to moderately damp, nutrient-rich ground. Marginal habitats and boundaries like rich fen borders and shores (also on the outer skerries in the Baltic); in the Scandes in the birch forest belt and (above the timberline) in willow thickets, at cliff-bases (where water supply is good) and at south-facing precipices. In mature forest usually sparse and often not flowering, thriving only in locally favourable places like pits from uprooted trees, scree slopes, boulders and cliff-ledges (especially where manured by leaf litter); often abundant after forest fires, clear-felling and thinning. Very hemerophilous (and indeed more conspicuous in man-made habitat than in natural ones); common along forest roads, on roadsides and railway embankments, on ruderal ground, at farms, in gravel pits and other disturbed ground, but only rarely in cultivated soil, e.g. as a garden weed. Favoured by disturbance, e.g. large-scale forestry methods, and raised nutrient levels, e.g. by increased nitrogen deposition, but sensitive to grazing, by cattle as well as by deer and elk; declining in forest habitats at least in southern S during the 1990’s due to an increase of game.
Biology. Vegetative propagation by the branching rhizomes is extensive, and true root suckers are also formed (Keating et al. 1982); the clones are often large and dense. The seeds are shortlived, but new stands are often established from seeds in disturbed spots.
Variation. Clones deviating in branching, leaf shape and colour and development are occasionally found in most provinces, more frequently in recently disturbed places. Variants with white or light pink petals occur in many places, but are especially well documented from S Nb, ÅsL, LyL, PL, LL and TL and F PeP, OP and U. Such variants usually have red sepals; more rarely sepals as well as petals are white. A monstrous variant where the flowers are replaced by short lateral inflorescences with pale, vestigial flowers was described by Danielsen (1966). It is known from a few scattered localities in southern N.
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2. Chamerion latifolium (L.) Holub Map
Holub, Folia Geobot. Phytotax. 7: 86 (1972). – Epilobium latifolium L., Sp. pl.: 347 (1753). – Chamaenerion latifolium (L.) Sweet (1830). – Type: Linnaean Herbarium 486.2 (LINN) lectotype, sel. by Raven in Rechinger, Fl. Iranica 7: 5 (1964).
D Storblomstret Gederams. F naalinhorsma. I eyrarós. N praktmjølke. S praktmjölke.
Rhizome branching, mostly oblique to erect and 3–5 mm thick; winter buds at old stem bases. Shoots (5–)10–40(–50) cm, erect or with ascending base, simple or sparsely branched above, often appearing branched from the base because of proliferation of several rhizome buds. Stem 1.5–5 mm thick, subterete with 2–4 inconspicuous or weakly raised lines, densely hairy with eglandular, erectopatent to incumbent hairs. Leaves subsessile, 15–60(–75) × 5–25 mm, lanceolate to elliptical, entire, with inconspicuous veins, somewhat glaucous, moderately to densely hairy with short eglandular hairs.
Inflorescences (1–)5–10(–25)-flowered racemes; bracts like the cauline leaves; pedicels at anthesis 3–15 mm, with ripe fruit up to 30 mm. Buds ellipsoidal, 8–15 mm. Flowers slightly zygomorphic. Sepals 10–18 × 4–8 mm, spreading at anthesis like the petals, dark purplish red. Petals 15–25 × 8–15 mm, not or slightly notched, reddish pink. Stamens subequal, in young flowers turned slightly upwards, later downwards; filaments (5–)9–15 mm; anthers (1.5–)2.5–3.2 mm. Style 4–10 mm, in young flowers turned downwards, later upwards. Stigma deeply 4-lobed. Capsules 30–60(–70) mm, densely pubescent with eglandular hairs. Seeds 1.5–2 × 0.5–0.6 mm, smooth to finely striate; neck 0.1–0.2 mm; seed hairs 10–12 mm. – Summer to early autumn.
2n = 72 (I IMi). [2n = 36, 72; natural triploid 54]
Distribution. MBor–MAlp. Alt. 1000 m (I IAu). – Only in I; fairly common throughout (except in some coastal areas as IVe Reykjanesskagi and INo Melrakkaslétta).
NE Russia, N Asia, N America including Greenland.
Habitat. Often covering large areas in gravelly river-beds; more rarely in gravelly mountain slopes and on rock ledges.
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