Geum macrophyllum
(largeleaf avens)

Largeleaf avens (Geum macrophyllum) are ordinary, almost weedy wildflowers, yet they impart a pleasant charm to the woodland wayside. With their widely spaced and sometimes missing petals, they often resemble the happy grins of gap-toothed youngsters. Individual largeleaf avens typically have five 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 stamens and pistils, 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 of its many pistils. 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.

Avens are herbaceous perennials that sprout anew each year from rhizomes below the soil. Their 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 lengthen into sharply toothed, well-divided leaflets while their petioles (leaf stems) shorten until they have disappeared entirely just beneath the blooms.

Largeleaf avens have 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 them in moist, lowland woodlands, although their range can extend to higher elevations. In Western Washington, largeleaf avens often share the same habitat as youth-on-age, or, piggyback plants (Tolmiea menziesii) and fringecups (Tellima grandiflora), forming a cheery trailside border or woodland edge. Like their neighbors, largeleaf avens bloom from late spring to mid summer.

Typical Western Washington habitat of largeleaf avens:

© 2023 Anthony Colburn. Images may not be used or reproduced in any form without express written consent.


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