achene

Carl Linnaeus was not kidding when he chose the name Ambrosia for it: achene, its nutritious fruit, provides lots of calories to wildlife.

From Scientific American ● Sep. 9, 2011

Style 3-cleft; achene triangular; stamens 3; spikelets many-flowered, flattened, the carinate scales decurrent upon the rhachis as scarious wings; spikes in simple or compound umbels.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray

Style undivided or 2-parted, filiform; ovule pendulous; fruit an achene, embryo curved.—Trees or shrubs, with milky juice, alternate leaves, and fugacious stipules.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray

Annual, twining or procumbent, low, roughish, the joints naked; leaves halberd-heart shaped, pointed; flowers in small interrupted corymbose racemes; outer calyx-lobes keeled; achene smoothish.—Cult. and waste grounds, common.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray

Scape 1–2° high; leaves linear to lanceolate, entire to dentate or laciniate; head often pubescent or villous; achene long-beaked.—Minn. to Neb. and southwestward.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Asa Gray