Apios americana Medic.

Ground Nut

Apios americana plant

Family - Fabaceae

Stems - Twining, thin, herbaceous, glabrous to appressed pubescent, terete, from rhizomes. Rhizomes often thickened into large tubers to +/-5cm in diameter.

Leaves - Alternate, odd pinnate with 3-7 leaflets, stipulate. Stipules linear, 5-6mm long, pubescent. Petiole thickened at base for 6-7mm, glabrous to sparse appressed pubescent, to +/-6cm long, with adaxial groove. Leaflets on short petiolules to 4mm long. Lateral leaflets ovate to ovate-lanceolate, entire, with some cilia on margins, glabrous above, glabrous to sparse pubescent below, acute to acuminate, to +6cm long, +2.5cm broad. Terminal leaflet more broad than lateral leaflets, on petiolule to 1.5cm long.

Apios americana leaves

Inflorescence - Axillary pedunculate racemes to +/-8cm long. Peduncles typically glabrous, to 5cm long. Pedicels to 4mm in flower, subtended by small pubescent bract, with prominent gland in axil with stem.

Apios americana inflorescence

Flowers - Corolla papilionaceous. Standard reflexed, deep purplish-maroon internally, lighter externally, whitish at base, 1cm long, 1.1cm broad. Wings deep brownish-purple. Keel lighter than other petals, greatly incurved, apex of keel tucked against the standard. Stamens 10, diadelphous. Stamen tube(connected filaments) white, glabrous. Anthers yellowish, .2mm long. Ovary pale green, 5-6mm long, pubescent. Style coiled as keel petals, white with green at apex, pubescent. Calyx glabrous, tubular, bilabiate. Upper lip with 3 lobes. Central lobe acute, 1.8mm long, with sparse pubescence externally. Lateral two lobes smaller, .6mm long. Lower lip with two shallow lobes. All lobes with minutely lacerate margins. Calyx tube 3mm long, green with some reddish tinge, glabrous internally. Fruit to +/-6cm long, -1cm broad.

Apios americana calyxCalyx.

Apios americana flowerFlower close-up.

Flowering - June - September.

Habitat - Wet meadows, streambanks, pond margins, moist woodlands.

Origin - Native to U.S.

Other info. - The plants thickened rhizome portions were a big hit amongst the Indians and used by settlers in this area. The rhizomes contain up to 3 times the protein of potatoes and can be boiled, fried, or roasted. The seeds are edible also. The plant is a fast growing perennial and, as stated above, prefers moist areas. I ate some of the rhizomes from this very plant while camping. I must admit, they could have used a little salt.

Photographs taken at Logan Creek, Ellington, MO., 8-1-04.