Flora of the Hawaiian Islands
Dicotyledon Literature for Sida spinosa
Lorence & Wagner, 2020.
   Malvaceae -- The Cacao, Linden, Mallow Family Bibliography
      Sida spinosa

Common name(s): prickly sida
General Information
DistributionOrigin uncertain, but perhaps native to tropical America. This morphologically variable species is now widely naturalized in tropical and warm temperate regions worldwide.In the Hawaiian Islands, naturalized on Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Hawai`i.

Erect annual, perennial herb, or subshrub, 0.3‒0.8 m tall; copiously minutely stellate puberulent, eventually glabrate.
Leaves petiolate; blade linear to narrowly oblong or ovate, 0.6‒7 cm long, 0.2‒1.7 cm wide, margin serrate to crenate, base obtuse to truncate; petiole usually ½ or less the length of blade, 0.2‒1.8 cm long; stipules filiform, 2‒5 mm long, each subtended by a short tubercle.
Inflorescences a solitary flower or flowers in clusters, often somewhat corymbose toward the ends of the branches. Flowers on slender pedicel, 0.2‒2.8 cm long; calyx strongly 10-ribbed, 4‒7 mm long; petals pale yellow to yellowish orange, 5‒6(‒7) mm long; staminal column included.
Fruit with 5 mericarps, 3‒4 mm long, grading apically into 2 antrorsely pubescent awns 0.5‒1.5 mm long, proximal abaxial and lateral walls strongly reticulate, apical surfaces smooth, puberulent.
Seeds ca. 1.5 mm long, glabrous or with a few hairs around the hilum.
2n = 14, 28.
Nancy Khan