Flora of the Hawaiian Islands
Dicotyledon Literature for Pilea microphylla
Lorence & Wagner, 2020.
   Urticaceae -- The Cecropia, Nettle Family Bibliography
      Pilea microphylla

Common name(s): artillery plant, rockweed
General Information
DistributionNative to southern Florida, the West Indies, Mexico, and south to tropical South America.In the Hawaiian Islands, naturalized on Midway, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Hawai`i.

Monoecious or dioecious, annual or short-lived perennial herb; stems succulent, sometimes slightly woody at base, prostrate-spreading or cespitose, 5‒50 cm long.
Leaves crowded throughout stem length, short-petiolate or subsessile; blade obovate, elliptic, oblanceolate, or oblong, 1.5‒10 mm long, 1‒4 mm wide, those of a pair often unequal in size, sometimes some branches with leaves of a pair equal or all leaves of plant equal, secondary veins 2‒3 on each side, often inconspicuous, adaxial surface with crowded elliptic cystoliths, abaxial surface finely reticulate, margin entire; petiole (0‒)1‒4 mm long, always shorter than the blade; stipules ca. 1 mm long.
Inflorescences a sessile glomerule or cyme, peduncle 1‒6 mm long. Staminate flowers 0.6‒1 mm long, calyx lobes glabrous, each with a blunt, abaxial, apiculate appendage; pistillate flowers 0.8‒1 mm long, outer calyx lobe slightly longer than others, with inconspicuous abaxial, apiculate appendages.
Fruit ellipsoid, compressed, 0.5‒1 mm long, slightly longer than the largest calyx lobe.
2n = 36.
Nancy Khan