Flora of the Hawaiian Islands
Dicotyledon Literature for Amaranthus viridis
Wagner et al., 1990, 1999; Lorence & Wagner, 2020.
   Amaranthaceae -- The Amaranth, Goosefoot Family Bibliography
      Amaranthus viridis

Common name(s): amaranth, pigweed, `aheahea, pakai, pakaikai, pakapakai (Ni`ihau), slender amaranth
General Information
DistributionWidespread in tropical and subtropical regions of the world.In the Hawaiian Islands, naturalized on Kure, Midway, Laysan, Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Kaho`olawe, Hawai`i.

Annual, monoecious herb; stems erect or occasionally ascending, 1‒8(‒10) dm long, sparingly to densely branched, striate, glabrous and usually becoming pubescent with multicellular hairs above.
Leaves petiolate; blade deltate-ovate to narrowly rhombic, 2‒7 cm long, 1.5‒5.5 cm wide, glabrous or abaxial surface pilose along the veins, apex usually narrow and with a small narrow emargination; petiole 1‒10 cm long.
Inflorescences a slender, axillary or terminal and often paniculate spike, sometimes in axillary clusters in proximal part of plant, both sexes mixed throughout the spikes, but pistillate flowers more numerous; bracts and bracteoles whitish, deltate-ovate to broadly lanceolate, membranous, with a short, pale or reddish awn. Flowers green, sepals 3(4), those of staminate flowers ovate-oblong, ca. 1.5 mm long, apex acute, mucronate, those of pistillate flowers narrowly spatulate to oblong, 1.3‒1.8 mm long, apex ± mucronate; stigmas 2‒3.
Fruit subglobose, 1.3‒1.5 mm long, not or only slightly exceeding the sepals, indehiscent or rupturing irregularly at maturity, conspicuously rugose throughout.
Seeds dark brown to black, ± shiny, slightly compressed, 1‒1.3 mm long, reticulate and with shallow outgrowths on the reticulum.
2n = 34.
Warren Wagner