Flora of the Hawaiian Islands
Dicotyledon Literature for Tribulus cistoides
Lorence & Wagner, 2020.
   Zygophyllaceae -- The Cresote Bush Family Bibliography
      Tribulus cistoides

Common name(s): caltrop, nohu, nohunohu
General Information
DistributionNative to the Old World, now a pantropical weed, often occurring in maritime habitats.In the Hawaiian Islands, indigenous to Kure, Midway, Pearl and Hermes, Lisianski, Laysan, French Frigate Shoals, Nihoa, Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Kaho`olawe, Hawai`i.

Click here for detailed USGS map by Jonathan Price
Perennial herb, prostrate to ascending; stems to several meters long.
Leaves short-petiolate; blade (1.5‒)3‒10 cm long, 5‒10(‒11) pairs; leaflets oblong to elliptic, 7‒28 mm long, 2.5‒12 mm wide, both surfaces moderately to densely sericeous to long-strigose, apex apiculate or rounded; petiole 5‒15 mm long; stipules subulate to falcate, 3‒9 mm long, 1‒4 mm wide.
Inflorescences with peduncle densely antrorsely strigose and hirsute, the latter hair type with pustulate bases. Flowers with lanceolate sepals , slightly unequal, 7‒14 mm long, 2‒5 mm wide, margin scarious; petals lemon yellow to bright yellow, deltate-obovate, 11‒26 mm long, 6‒15 mm wide; outer nectaries green, bilobed, intrastaminal ones connate into an annular ring around ovary base; ovary long-strigose.
Fruit 8‒15 mm in diameter, mericarps 5, abaxially crested and tuberculate, bearing 2 stout hard spines, 5‒10 mm long, sometimes also with 2 smaller spines near base, rarely spine 1 or absent, crests short-hirsute, hairs with pustulate bases.
2n = 12, 36*.
Nancy Khan