The largeleaf avens (Geum macrophyllum) is an ordinary, almost weedy wildflower, yet imparts a pleasant charm to the woodland wayside. With its widely spaced and sometimes missing petals, its blooms often resemble the happy grins of gap-toothed youngsters.
Blooms, Fruits, and Seeds
Individual largeleaf avens typically have five deep yellow petals, although it is not uncommon for them to have more or fewer. Blooms are borne in small clusters at the tips of their stems.
The center of each avens is crowded with stamens1A stamen is the male reproductive structure of a flower, consisting of an anther in which pollen is produced and usually a slender filament that attaches it to the flower. An individual flower typically has many stamens. and pistils2A pistil is the female reproductive structure of a flower, consisting of the stigma, which receives pollen, the ovary, in which seeds are formed, and the style, which connects the ovary and the stigma., the plant’s male and female reproductive structures, respectively. After the petals drop, the center turns into a bristling pinwheel that is surprisingly wiry to the touch. The bristles are the bloom’s hardened styles, or, the stalks that loft its pollen-collecting stigmata atop its many ovaries. Each style is attached to an achene, a small, dry fruit that forms a protective case around the single seed it contains. The other end of each achene is connected to a central core, similar to those of well-known achene-producing flowers, dandelions and strawberries. (In the case of strawberries, the core is what we eat — the actual fruits are the attached achenes, or, “seeds.”) The twisted hook at the tip of each style enables the achene to snag the clothing or fur of unsuspecting passersby to be carried abroad, which facilitates seed distribution.
Plant Features
The avens is an herbaceous perennial that sprouts anew each year from rhizomes3Rhizomes are thickened stems that grow along or under the soil surface and bear shoots above and roots below. below the soil. The foliage transitions significantly from the basal leaves to those just beneath the blooms. The leaves just above the rhizome are long-stemmed and divided into sets of rounded leaflets, each with three lobes and graduated in size toward the terminal leaflet. (The avens shown here are var. macrophyllum, which has basal leaves with less divided individual leaflets. It is chiefly found west of the Cascade Mountains in Western Washington. The terminal basal leaflet of var. perincisum, which grows east of the Cascades, is more deeply divided into three distinct lobes.) As the plant grows, the stem leaves elongate into sharply toothed, well-divided leaflets while their leaf stems4The stem that attaches a leaf blade to a plant stem is called a “petiole”. shorten until they have disappeared entirely just beneath the bloom cluster.
Range and Habitat
The largeleaf avens has a circumboreal distribution, spanning the great northern forests of Europe, Asia, and North America and extending down the Pacific coast and Rocky Mountains into New Mexico and Baja California. Look for it in moist, lowland woodlands, although its range can extend to higher elevations. In Western Washington, largeleaf avens often shares the same habitat as youth-on-age, or, piggyback plant (Tolmiea menziesii) and the fringecup (Tellima grandiflora), forming a cheery trailside border or woodland edge. Like it neighbors, the largeleaf avens blooms from late spring to mid summer.
Typical Western Washington habitat of largeleaf avens:
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