Murdannia stenothyrsa (Diels) Hand.-Mazz.

Murdannia stenothyrsa may be better treated as a subspecies of M. simplex because they differ only in a few quantitative characters and seem to be altitudinally vicarious. In the protologue of Aneilema stenothyrsum the capsule was described as having 1 seed per valve. Some specimens from Yunnan (including the type locality) and Sichuan, which are consistent with the protologue, have 2 seeds per valve.

Herbs perennial. Roots fibrous, robust, 2--3 mm in diam., densely lanate. Rhizomes absent. Main stem undeveloped, short, with basal, rosulate leaves; fertile stems 2--4, arising from base of main stems, usually erect, sometimes ascending, to 50 cm. Basal leaves with sheath sparsely hirsutulous throughout, sometimes proximal ones hirsute only along mouth slit; blade linear, 15--35 × 0.6--1.5 cm, glabrous. Cauline leaves often 2 or 3, rarely more; proximal leaf blades to 12 cm, distal ones shorter, sometimes only ca. 10 mm, glabrous. Cincinni several, to 2 cm, forming narrow panicles ca. 5 cm; peduncle ca. 10 mm; involucral bracts ovate or ovate-lanceolate, less than 10 mm, membranous, caducous; bracts subequaling sepals, caducous; flowers pendulous in bud, ascending at anthesis; pedicels straight, ca. 5 mm in fruit. Sepals elliptic, 5--6 mm. Petals purple or blue, obovate-orbicular, ca. 8 mm. Fertile stamens 2; filaments lanate; staminodes 3; antherodes 3-sect. Capsule ovoid-globose, trigonous, 6--7 mm. Seeds 2 per valve, brown-black, white radiate verrucose. Fl. Jun--Oct.

C and SW Sichuan (Hanyuan Xian, Xichang Xian), C and W Yunnan.

* Open mountain slopes, forests, by rice fields; 1700--2700 m.

Aneilema stenothyrsum Diels, Notes Roy. Bot. Gard. Edinburgh 5: 297. 1912.

Murdannia stenothyrsa là một loài thực vật có hoa trong họ Commelinaceae. Loài này được (Diels) Hand.-Mazz. mô tả khoa học đầu tiên năm 1936.

树头花（学名：Murdannia stenothyrsa）是鸭跖草科水竹叶属的植物，为中国的特有植物。分布于中国大陆的四川、云南等地，生长于海拔1,700米至2,700米的地区，多生长于杂木林内、开旷山坡和水稻田边，目前尚未由人工引种栽培。