Chamaenerion angustifolium |
Onagraceae |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
fireweed, rosebay willowherb, épilobe à feuilles étroites |
evening-primrose family |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Habit | Herbs robust, caudex woody, often forming large clones by horizontal rhizomes 0.5–2 cmdiam., extending 0.5–5 m, forming shoots from caudex and along rhizomes. | Herbs, annual or perennial, shrubs, or subshrubs, [lianas or trees], terrestrial, amphibious, or aquatic, unarmed, not clonal; often with epidermal oil cells, usually with internal phloem, abundant raphides in vegetative cells. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Stems | erect, terete, usually unbranched, rarely branched distally, 20–200 cm, glabrous or sparsely to densely strigillose, often exfoliating proximally. |
erect to decumbent or prostrate. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Leaves | usually spirally arranged, very rarely subopposite proximally; petiole 0–7 mm; blade lanceolate to linear or proximally oblong to obovate, (3–)5–23 × 0.3–3.4 cm, proximal ones much reduced, base obtuse or cuneate to attenuate, margins entire or scarcely denticulate, apex attenuate-acute, lateral veins 10–25 on each side of midrib, diverging nearly at right angles, confluent into ± prominent submarginal vein, surfaces glabrous or strigillose on abaxial midrib; bracts much reduced and linear. |
usually deciduous, usually alternate or opposite, sometimes whorled, simple, usually cauline, sometimes basal and forming rosettes; stipules present, intrapetiolar, usually caducous, relatively small, or absent (tribes Epilobieae and Onagreae); sessile or subsessile to petiolate; blade margins usually entire, toothed, or pinnately lobed, rarely bipinnately lobed. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Inflorescences | erect racemes, 5–50 cm, glabrous or strigillose. |
axillary, flowers solitary, leafy spikes, racemes, or panicles. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Flowers | nodding in bud, erect at anthesis, opening laterally; buds oblong to oblanceoloid, 7–14 × 3–35 mm; sepals purplish green, oblong-lanceolate or upper pair somewhat oblanceolate, 8–19 × 1.5–3 mm, base usually attenuate, rarely ± clawed, apex acuminate or attenuate, canescent abaxially, glabrous adaxially; petals usually rose purple to pale pink, very rarely white, obovate to narrowly obovate or nearly rotund, 9–25 × 3–15 mm, upper pair often ± longer and broader, base attenuate, apex entire or shallowly emarginate; filaments pink, 7–15 mm, subequal; anthers red to rose purple, oblong, 2–3 × 1–1.7 mm; ovary 6–25 mm, surface densely canescent; nectary disc raised 0.5–1 mm on ovary apex, 2–4 mm diam., smooth or slightly 4-lobed, glabrous; style sharply deflexed initially, later erect, white or flushed pink, 8–16 mm, proximally villous; stigma spreading to revolute, lobes 3–6 × 0.6–1 mm, surfaces white, densely dry-papillose. |
usually bisexual, (protandrous in Chamaenerion, Clarkia, Epilobium, [and most species of Lopezia]; protogynous in Circaea and Fuchsia), sometimes unisexual (gynodioecious or dioecious, [subdioecious]), usually actinomorphic, sometimes zygomorphic, (2–)4(–7)-merous; perianth and androecium epigynous; sepals persistent after anthesis (in Ludwigia), or all flower parts deciduous after anthesis; floral tube present or absent in Chamaenerion, Ludwigia, [and most species of Lopezia]; sepals usually green or red, rarely pink or purple, valvate; petals present, rarely absent, often fading darker with age, imbricate or convolute, sometimes clawed; nectary present; stamens 2 times as many as sepals and in 2 series, antisepalous set usually longer, rarely all equal (Chamaenerion), or as many as sepals, [in Lopezia reduced to 2 or 1 plus 1 sterile staminode]; filaments distinct; anthers usually versatile, sometimes basifixed, dithecal, polysporangiate, with tapetal septa, sometimes also with parenchymatous septa, opening by longitudinal slits, pollen grains united by viscin threads, (2 or)3(–5)-aperturate, shed singly or in tetrads or polyads; ovary inferior, usually with as many carpels and locules as sepals, rarely 1 or 2 (Circaea and Gayophytum), septa sometimes thin or absent at maturity; placentation axile or parietal; style 1, stigma 1, with as many lobes as sepals or clavate to globose, papillate or not, and wet with free-running secretions to dry without the secretions; ovules 1 to numerous per locule, in 1 or several rows or clustered, anatropous, bitegmic. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Fruit | a loculicidal capsule or indehiscent berry or nutlike. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Capsules | 4–9.5 cm, densely appressed-canescent; pedicel 0.5–3 cm. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Seeds | narrowly obovoid to oblong, 0.9–1.3 × 0.3–0.4 mm, chalazal end tapering abruptly to very short neck (to 0.1 mm), surface appearing smooth and often shiny, but irregularly reticulate; coma 10–17 mm, white or dingy, dense, not easily detached. |
smooth or sculptured, sometimes with a coma or wings, with straight, oily embryo, 4-nucleate embryo sac, endosperm absent. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
x |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
2n | = 36, 72, 108. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Chamaenerion angustifolium |
Onagraceae |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Distribution |
North America; n Mexico; Europe; Asia |
North America; Mexico; Central America; South America; West Indies; Bermuda; Eurasia; Africa; Atlantic Islands; Indian Ocean Islands; Pacific Islands; Australasia; nearly worldwide; primarily New World |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Discussion | Subspecies 2 (2 in the flora). Chamaenerion angustifolium, which in North America is known mostly as fireweed, is a widespread circumpolar, circumboreal species that can be locally dominant, often in disturbed habitats, particularly following fires (T. Mosquin 1966, 1967; G. Henderson et al. 1979). In addition to producing numerous, highly vagile, comose seeds, aggressive rhizomatous growth enables it to survive clonally and spread rapidly after fires (L. E. Vodolazskij 1979). As succession proceeds, production of the familiar spikes of magenta flowers is inhibited, but fireweed often persists in non-flowering condition even in relatively mature forests, where it is able to sprout and spread quickly following disturbance. The species is one of the few within the genus and tribe to form true rhizomes (R. C. Keating et al. 1982), enabling it to colonize large areas very rapidly. Polyploidy is well documented in Chamaenerion angustifolium, but unlike the similar situation in C. latifolium (T. Mosquin and E. Small 1971), diploid and tetraploid populations differ morphologically and have partially overlapping, but distinct, geographical ranges (Mosquin 1966; Chen C. J. et al. 1992). The diploid subsp. angustifolium occupies the northern part of its range, in North America across Canada and interior Alaska, and in Asia across Siberia and northern Europe, ranging southward at higher elevations. Farther south in Eurasia and North America, it is replaced by the tetraploid subsp. circumvagum (Mosquin 1966). Hexaploid (n = 54) populations have been detected only in Japan, and cannot be distinguished morphologically from tetraploids. B. C. Husband and D. W. Schemske (1998), Husband and H. A. Sabara (2004), and Sabara et al. (2013) have documented population segregation and mixing in contact areas between the two ploidy levels, including populations with a single cytotype, a high proportion of mixed populations, and presence of triploids (n = 27), but at low levels, indicating strong reproductive isolation between cytotypes. The floral phenology of Chamaenerion angustifolium was described in 1793 by C. K. Sprengel (P. Knuth 1906–1909, vol. 2) as a classic example of protandry. The flowers are presented in tall spikes, opening from the base of the spike, initially with stamens erect and style sharply reflexed. By the second or third day after opening, the stamens reflex as the style straightens into the floral axis, the four lobes of the stigma spread open, and nectaries commence production. Bees start at the lowest flowers in search of nectar, moving up the spike until there is no more nectar, by which time they are well dusted with pollen, which they bring to the lower functionally (female) flowers of the next spike. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Genera 22, species 664 (17 genera, 277 species in the flora). Members of the Onagraceae are especially richly represented in North America. The family comprises annual and perennial herbs, with some shrubs and a few small to medium-sized trees. Most species occur in open habitats, ranging from dry to wet, with a few species of Ludwigia aquatic, from the tropics to the deserts of western North America, temperate forests, and arctic tundra; some species of Epilobium, Ludwigia, and Oenothera can be weeds in disturbed habitats. Members of the family are characterized by 4-merous flowers (sometimes 2-, 5-, or 7-merous), an inferior ovary, a floral tube in most species, stamens usually two times as many as sepals, and pollen connected by viscin threads. Flowers are usually bisexual, sometimes unisexual, and plants are gynodioecious, matinal, diurnal, or vespertine, self-compatible or self-incompatible, often outcrossing and then pollinated by a wide variety of insects or birds, or autogamous (P. H. Raven 1979; W. L. Wagner et al. 2007). Onagraceae are known in considerable systematic detail, and information is available on comparative breeding systems and pollination biology, on chromosome numbers and cytogenetic relations, often involving translocations, and on vegetative, floral, and seed anatomy, palynology, and embryology. The phylogeny of the family is known in reasonably good detail, with most parts of the trees generally well-supported. The suprageneric and generic classification presented by W. L. Wagner et al. (2007) differs in a number of ways from the previous classification (P. H. Raven 1979, 1988). Onagraceae are divided into two subfamilies based on a fundamental basal split recognized in all phylogenetic studies (R. H. Eyde 1981; P. C. Hoch et al. 1993; R. A. Levin et al. 2003, 2004; V. S. Ford and L. D. Gottlieb 2007), with Ludwigia on one branch (as Ludwigioideae), and the rest of the family on a second branch (as Onagroideae). Onagroideae are subdivided into six tribes: Circaeeae (including Fuchsieae), Epilobieae, Gongylocarpeae, Hauyeae, Lopezieae, and Onagreae. The Epilobieae and Onagreae are diverse; together they constitute fully two-thirds of the species in the family and include 15 of the 22 genera. The classification following Wagner et al. can be viewed on the Onagraceae web site by Wagner and Hoch at http://botany.si.edu/Onagraceae. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Key |
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Source | FNA vol. 10. | FNA vol. 10. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Onagraceae > subfam. Onagroideae > tribe Epilobieae > Chamaenerion | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Sibling taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Subordinate taxa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Synonyms | Epilobium angustifolium, Chamerion angustifolium, Pyrogennema angustifolium | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | (Linnaeus) Scopoli: Fl. Carniol. ed. 2, 1: 271. (1771) | Jussieu | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Web links |
|
|