Description

Key Characters:

Growth Form: Hawaiian cotton shrubs 0.5–1.5 m tall, softly white tomentose.

Stems:

Roots:

Leaves: Leaves simple. Alternate. Blades wider than long, usually 3–10(–12) cm wide, 3–lobed or some–times 5–lobed to about the middle, the lobes ovate, acute or subacuminate. Surfaces tomentose. Margins lobed but otherwise entire. Midvein on lower surface with basal gland absent or obscure. Petioles present. Stipules subulate, 0.5–0.8 cm long, caducous.

Flowers: Flowers solitary or few in short cymes, pedicel nectaries absent; involucral 3 bracts ovate, 15–25 mm long, dentate, with 5–9(–12) acute teeth. Flowers bisexual (perfect). Calyx erosely truncate, 7–9 mm long, sepals connate, the lobes valvate in bud. Corolla actinomorphic to moderately zygomorphic, corolla of 5 petals, bright yellow, without a maroon spot, fading greenish, 2–3.5(–4) cm long, campanulate to funnelform, the corolla of 5 petals, obovate, distinct from each other but adnate at base to staminal column, convolute in bud. Stamens 5 to numerous, monadelphous, forming a staminal column, staminal column included, 5-toothed at apex; antheriferous for most of its length or only in upper 1/2; anthers monothecal. Pollen globose, echinate. Ovary superior, 3-5-celled, the carpels borne in a single whorl or rarely seemingly superposed whorls, placentation axile; ovules several per cell; style exceeding the staminal column, unbranched, clavate; stigma 3-5-lobed, decurrent.

Fruit: Loculicidally dehiscent; usually glabrous capsules; 3–celled; coriaceous to woody; ovoid; cuspidate; 1.2–1.8 cm long; black–pitted. Seeds 2–4 per cell; ca. 5 mm long; densely covered with reddish brown lint; turbinate; with or without endosperm.

Ploidy: 2n = 52*

Habitat: Occurring primarily in arid; rocky; or clay coastal plains.

Elevation Range: 0–120 m.

Historical Distribution

Images

Synonyms (5)

Gossypium hirsutum f. tomentosum (Nutt. ex Seem.) Roberty (1950)

Gossypium parvifolium Nutt. ex Seem. (1865)

Gossypium sandvicense Parl. (1866)

Gossypium tomentosum var. parvifolium Nutt. ex G. Watt (1907)

Hibiscus tomentosus (Nutt. ex Seem.) Kuntze (1891)

Uses and Culture

USES

Flowers for yellow dye and leaves for green dye for kapa (Abbott 1993:66).
For treating the illness nahu‘aki o ka opu mai na makua mai ("gripping stimach ache"). To prepare, one needs to dry the flowers of ma‘o, nohu (Tribulus cistoides), ‘ilima (Sida fallax), and pua aloalo (cf. Hibiscus arnottianus) in the sun on niu (coconut, Cocos nucifera). The tap roots of ma‘o, ‘uhaloa (Waltheria indica), pōpolo (Solanum americanum), ‘ohi‘a ‘ai (Syzygyium malaccense), kōhonua‘ula (red sugarcane, Saccharum officinarum), and koali (Ipomoea spp.) are mashed and heated into a liquid form. The dried leaves are drunk with the liquid mixture (Chun 1994: 217–218).
Greenish (leaves), yellow (petals)

PROPAGATION/CULTIVATION

Gossypium tomentosum seeds are enclosed in a 3 part capsule. This oval woody fruit is 1/2 to 3/4 inch long and contains 6 to 12 seeds. The small seeds are covered with reddish brown fuzz.
Gossypium tomentosum grows easily from seed. Mew recommends scarification (penetrating the seed coat) to improve germination. Others recommend soaking the seeds in water for 24 hours to improve germination time. NTBG recommends cold water treatment; Bornhorst suggests hot water. Plant the seeds in a well-draining mix such as 2 parts perlite to 1 part sterile potting mix or a mix of 1 part perlite to 1 part peat moss. The pots should be placed in light shade and kept moist, but not over watered.
In his germination studies, Obata found that untreated seeds of Gossypium tomentosum had extrememly variable germination rates ranging from 1 to 75%. (Bornhorst 1996; Mew 1987; NTBG 1992; Obata 1967; Rauch 1997; Wagner 1990)
Gossypium tomentosum can be grown from cuttings. Criley reports success with both softwood and semi-hardwood terminal cuttings. He recommends using a rooting hormone of 2,000 parts per million (ppm) indolebutyric acid (IBA) in either a liquid or a talc dust form. Criley suggests either 1 part coarse perlite to 1 part vermiculite or 100% vermiculite as a rooting medium. His work was done using an intermittent mist system which was on for 6 to 8 seconds every 5 or 6 minutes; cuttings were rooted under 30% shade. Cuttings root in 3 to 4 weeks. (Criley 1998; Criley 1999)
Gossypium tomentosum can be grown from air layers. (Bornhorst 1996; Rauch 1997) [Data from Herring, E. C., & Criley, R. A. (2003). The Hawaiian Native Plant Propagation Web Site: Developing a Webbased Information Resource. HortTechnology, 13(3), 545-548. https://www.ctahr.hawaii.edu/hawnprop/]