Aquatic and Wetland Vascular Plants of the Northern Great Plains
26. Rosaceae, the Rose Family
1. Geum L.-- Avens1. Geum rivale L. -- Water or purple avens
Erect perennial herb from a stout rhizome, 3-6(10) dm tall, sparingly hirsute throughout, also puberulent above with some short, glandular hairs. Principal leaves basal, pinnately compound, 1-4.5 dm long including the stipular-winged petiole; leaflets (5)7-15, the terminal 1-3 much larger than the others, shallowly lobed and coarsely dentate, terminal leaflet broadly cuneate-obovate to subrotund in outline, 2.5-10 cm long, 3-12 cm wide; cauline leaves 2-5, much reduced upward, pinnate below to 3-lobed above, stipules foliaceous. Flowers 3-9 in a cymose inflorescence, nodding to erect, the pedicels densely glandular-puberulent and hirsute; sepals 5, sometimes initially green but always purple in flower, ascending in flower to spreading or reflexed in fruit, triangular, 6-10 mm long, acute to acuminate, alternating with 5 shorter, linear-oblong bractlets; petals 5, yellowish to pinkish with purple veins, erect, broadly retuse, tapered to a clawed base, about equaling to a bit shorter than the sepals; stamens numerous; carpels many, separate, styles long and slender with a hooked joint above the middle, the portion above the joint deciduous, the slender lower portion persistent and curved or deflexed in fruit, 6-10 mm long, hirsute and glandular-puberulent; receptacle short-cylindric, on a short stipe; hypanthium purple, saucer-shaped, 3-4.5 mm long, hirsute and glandular-puberulent. Fruit an aggregate of long-beaked achenes, the fruiting head globose; achene bodies fusiform, 3-4 mm long, hirsute. May--Jul. Swampy and boggy places, fresh wet meadows; rare, with records from Pembina Co., ND, Day Co. and the Black Hills, SD; (Newf. to B.C., s to NJ, IN, MO, SD, NM and WA).
Geum aleppicum Jacq., yellow avens, is a more common species that occurs throughout our region and is sometimes encountered on stream banks, alluvial deposits and in wet meadows, though it is most characteristic of moist woodlands. It differs from G. rivale in its typically larger stature, green calyx and distinctly yellow petals.
 Geum rivale. |
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