fireweed

not listed

N4N5 - Apparently Secure to Secure

SNR - Unranked

not listed

FAC - Facultative

FAC - Facultative

FAC - Facultative

Fireweed (ssp. angustifolium) is an erect, perennial, 8″ to 52″ tall forb that rises usually on a single aerial stem from a rhizome-like underground stem and fibrous roots. It often forms large colonies.

The stems are erect, usually unbranched, and round or somewhat angular in cross section. They are leafy; hairless or nearly hairless below the inflorescence; and green, sometimes becoming reddish near the top in strong sunlight.

The leaves are alternate, numerous, and crowded. They are stalkless or nearly stalkless, narrowly lance-shaped or linear lance-shaped, 2¾″ to 5½″ long, and ¼″ to ½″ wide. The leaf blades are broadly angled or almost rounded at the base and taper to a point at the tip. The upper and lower surfaces are hairless, even on the midvein. There is a prominent midvein and 10 to 25 lateral veins that run into a single submarginal vein. The submarginal vein is distinct but the lateral veins often are not. The margins are untoothed or obscurely untoothed.

The inflorescence is a 3″ to 8″ long, unbranched cluster (raceme) of up to 15 or more stalked flowers at the end of the stem. The flowers nod at the end of a long, magenta-colored stalk when in bud. They are spreading to almost erect when in bloom.

Each flower is ¾″ to 1½″ in diameter. There are 4 sepals, 4 petals, 8 stamens and 1 style. The sepals are spreading, narrowly lance-shaped, ¼″ to ⅝″ long, and similar in color but darker than the petals. The petals are pink to magenta, rarely white. They are ⅜″ to ⅝″ long and ⅛″ to ⅜″ wide. They are narrowed at the base and broad near the tip. The stamens have long white filaments and dark magenta anthers. The style has a 4-lobed stigma.

The fruit is a straight, cylinder-shaped, 1½″ to 3″ long capsule with many seeds.

8″ to 52″

Pink or magenta

Fireweed (Chamaenerion angustifolium ssp. circumvagum) is often taller, up to 78″. The stems are minutely hairy, at least near the top. The leaves are larger and are usually hairy on the midvein below. They are on short but distinct stalks. The leaf blades are wedge-shaped at the base and usually blunt at the tip. The lateral veins are distinct. The flower petals are much larger.

Moist; roadside ditches, disturbed places, especially after a fire. Full or partial sun.

July to September

The flowers in the inflorescence mature from the bottom up. The stamens are erect at first and the style is sharply bent backward. After one or two days, the stamens bend backward, and the style straightens and opens up. Bees visiting the plant start at the bottom of the inflorescence and work their way to the top. When there is no more nectar to be collected, they proceed to the next inflorescence, again starting at the bottom. This system of male flower parts developing before female parts is known as protandry. It ensures that the plant will not self-pollinate.

Sources

4, 7, 29, 30.

USDA PLANTS shows C. a. ssp. angustifolium very common in Minnesota, concurrent with the range of its parent species, and C. a. ssp. circumvagum present in just seven scattered counties. GRIN shows the situation reversed, with C. a. ssp. angustifolium native to Canada and the northwestern United States and possibly also to Minnesota. The map at left does not include the USDA PLANTS data.

Native

Species in the genus Chamaenerion were originaly placed in the genus Epilobium. A group of several species was later separated from Epilobium as the new genus Chamaenerion. Recently it was determined that the name Chamaenerion was invalid “because it was derived from pre-Linnean sources and is synonymous with Epilobium,” and the genus name was shortened to Chamerion. A more recent clarification of the internationational Code of Botanical Nomenclature (ICBN), now the International Code of Nomenclature (ICN), “correctly argued that the name of the segregated genus should be Chamaenerion.”

Today (2023) there is little agreement as to the proper placement of the group.

ITIS and USDA PLANTS use the name Chamerion angustifolium.

NCBI, GRIN, GBIF, BONAP, Tropicos, Flora of North America, and iNaturalist use the name Chamaenerion angustifolium.

Plants of the World Online and World Flora Online use the name Epilobium angustifolium.

Inflorescence

Flower