Arachis hypogaea
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Description
Well-developed taproot with many lateral roots. Stem is up to 80 cm long, yellowish pubescent or nearly glabrous. The leaves are spirally arranged, pinnate with two opposite pairs of leaflets and no terminal leaflet. Petioles are 1.5-10 cm long, with sparse trichomes. Petiolules are 1-10 mm, velutinous. Leaflets are ovate-oblong to obovate, 1-7 x 0.5-3 cm, entire, both surfaces with long trichomes, base almost rounded, margin ciliate, apex obtuse, emarginated or mucronate. Stipules are prominent, linear-pointed, 1.5-4 cm long, covered by fine soft hairs. Inflorescence is an axillary, 2-5-flowered spike. Bracts are lanceolate, apex acuminate. Bracteoles are lanceolate, ca. 5 mm. Flowers are papilionaceous, bisexual, sessile, 5-10 mm long. Calyx tube is 4-6 cm long (elongates as bud develops), very slender and often mistaken for pedicel. Corolla is pale to golden yellow or orange-red, rarely white. Standard is spreading, apex emarginated. Wings are distinct, oblong to obliquely ovate. Keel is distinct, long ovate, shorter than wings, bent inwards, apex acuminate to beaked. Flowers are most abundant at lower nodes. Fruit is an oblong or sausage-shaped geocarpic legume, 1-8 cm × 0.5-2 cm, thick-walled, borne at the tip of an elongated fruit stalk (‘peg’) up to 20 cm long, 1-6-seeded. Fruit surface is constricted to varying degrees between the seeds and reticulately veined. Seeds are cylindrical to oblong, 1-2 cm × 0.5-1 cm, with pointed or flattened ends, enclosed in a thin papery seed coat ranging in colour from white to deep purple.

The map represents observations of this taxon, but it may not be used as a distribution map.
- Total squares
- maapähkinä (Finnish)
- jordnöt (Swedish)
- 2019
- Mikko Piirainen
- Vascular plants