Flora of the Hawaiian Islands
Dicotyledon Literature for Sida rhombifolia
Lorence & Wagner, 2020.
   Malvaceae -- The Cacao, Linden, Mallow Family Bibliography
      Sida rhombifolia
General Information
DistributionA polymorphic, pantropical weed.In the Hawaiian Islands, naturalized on Midway, Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Kaho`olawe, Hawai`i.

Erect subshrub, 0.5‒1.5 m tall; glabrate to cinereously stellulate pubescent, sometimes also with simple hairs.
Leaves short-petiolate; blade rhombic to elliptic or oblong-ovate, usually 1.5‒6(‒8) cm long, margin serrate distally, entire toward base, base cuneate or sometimes obtuse; petiole much shorter than blade; stipules of a pair similar in shape and size, filiform to linear, 3‒10 mm long.
Inflorescences a solitary flower in the leaf axils, sometimes appearing corymbose at the ends of the branches. Flowers on filiform pedicel, 1‒4 cm long; calyx strongly ribbed, 4‒7 mm long, lobes acute to acuminate; petals yellow or yellowish orange, 7‒10 mm long; staminal column included.
Fruit depressed ovate, apiculate, 4‒6 mm in diameter, glabrate or stellulate pubescent, mericarps (7‒)8‒10(‒14), 2.5‒3.5 mm long, apical beak or spine absent or 0.2‒2.5 mm long, lateral and abaxial surfaces smooth to rugose reticulate.
Seeds brown, 1.5‒2.4 mm long, 1.1‒1.9 mm wide, 0.8‒1.9 mm thick, glabrous or minutely white pubescent around the hilum.
2n = 14, 16, 18, 28, 36.
Nancy Khan