Commelina polygama Roth in Roem. & Ust., Bot. Mag. 4: 14. 1790; Henry, List Pl. Formos. 98. 1954.
Annual herbs. Roots fibrous. Stems branched, prostrate at base, erect above, rooting at nodes, puberulous along a line decurrent from the sheath. Leaves sessile to subpetiolate; blade lanceolate, 5.5-8 cm long, 1.5-2 cm wide, apex acuminate, base oblique, puberulous, scabrescent at margins; sheath cylindrical, with red stripes, puberulous or pilose at margins. Prophyll ca. 1.5 cm long, diam. 3 mm. Inflorescences terminal, upper cincinnus with 1 enserted male flower; lower cincinnus with 1-3 bisexual flowers; spathes broadly cordate, folded, ca. 1.7-2.6 cm long, ca. 2.5 cm wide, apex acute, base cordate, veinlets conspicuous, puberulous; bracteoles falling off early; peduncles 1.7-2.5 cm long; pedicels ca. 3-4 mm long, erect in anthesis and bent in fruiting. Flowers zygomorphic, bisexual; sepals 3, greenish, persistent, elliptic, concave, unequal, the anticous 2, basally fused, elliptic, 4.5-5 mm long, 3-3.7 mm wide, glabrous; the posticous one lanceolate, ca. 4.5 mm long, ca. 2.2 mm wide; petals 3, free, unequal, the lateral petals 2, indigo, equal, planar, clawed, the limb broadly ovate, ca. 10 mm long, 8-10 mm wide, apex acute, base cuneate-cordate, the claw ca. 3 mm long; the medial petal white, ca. 6 mm long, ca. 2 mm wide; fertile stamens 3, anticous, unequal, the lateral two, anther maroon to indigo, elliptic, base sagittate, ca. 2 mm long, filament ca. 10-12 mm long; the medial one, anther yellow, connective maroon, elliptic, base hastate, ca. 2.5 mm long, filament ca. 5-6 mm long; staminodes 3, posticous, all alike, antherodes cruciate, ca 2 mm long, filament ca. 3 mm long, with 2 lateral abortive pollen sacks; ovary ellipsoid, ca. 2 mm long; style ca. 1.3 cm long. Capsules bilocular, 2-valved, dehiscent, brown, ellipsoid, ca. 6-7 mm long, locules 2-seeded, glabrous. Seeds brown, deltoid in outline, dorsiventral, ventral surface planar, dorsal convex, ca. 2.5-3.5 mm long, ca. 2.5 mm across, reticulate, scrobiculate, densely covered with smaller farinose granules and sparse with larger farinose granules. Chromosome number: n = 44.
Fuchien: Lienchiang Hsien: Chukuang Hsiang : Tungchu: near the lighthouse. On semi-shaded roadside, elev. ca. 10 m, Liu & Ho 676 (TNU,HAST); Peikan Hsiang : along the road near Paishakang, elev. ca. 20 m, Liu & Ho 596 (HAST).
Taiwan
Taoyuan: Fuhsing District: Hsiayun, weeds in depressed, swampy area by an aboriginal village, elev. ca. 350 m, Peng 10273 (HAST); Fuhsing District: Lower Paling to Lalashan, elev. ca. 800-1600 m, Peng & Hu 12118 (HAST); en route from Upper Paling to entrance of Lalashan Recreation Area, elev. ca. 1000 m, Peng 11030 (HAST).
Hsinchu: Wufeng District: en route from Tuchang to Kuanwu; ca. 12.5 km S of Tuchang, elev. ca. 1280 m, Peng 9380 (HAST).
Miaoli: Malabangshan, elev. ca. 825-1000 m, Huang et al. 15609 (TAI).
Taichung: Lishan, Wu s. n. Sep. 27, 1996 (TAIF); same loc., Ho 285 (HAST).
Nantou: Chitou, elev. ca. 900 m, Hsu 6232 (TAI); Between Chitou & Sunlinksea, elev. ca. 1100-1600 m, Peng 5405 (HAST); Hsinyi Hsiang: Peiyushan, cut from Shalihsienhsi Forest Road through a valley up to a mt. ridge of ca. 1700 m alt. Broadleaf forest in valley, elev. ca. 1300-1700 m, Chiang et al. 91 (HAST); Hsinyi Hsiang: en route from Yunlung Fall to Yinu Fall. Broadleaf forest, elev. ca. 1300-1500 m, Chen et al. 137(HAST); Lushan, Lee et al. s.n. Jul, 1974 (TNU); Mayfeng. Waste field, elev. ca. 2400 m, Peng 9111 (HAST); Musya-Santinozyo-Miharasi, Masamune et al. s. n. Aug. 2, 1939 (TAI); Mt. Nengkao, Kao 5714 (TAI); Sanlinchi, Huang & Tson 9985 (TAI); same loc., Huang 98 (TAI); Shini District: Shenmu Village: Tapingting, elev. ca. 1300 m, Peng 6944, 7771 (HAST); Suaili to Tawuan, Kuoh s.n. Aug, 8 1969 (TAI); Sun-moon-lake, Wu-teng., Chaw 178 (HAST); Tung-Pu, elev. ca. 1120m, Huang 1586 (TNU); Enroute from Tungpu Hot Spring to Kuankao, elev. ca. 1500 m, Peng 8065 (HAST); Enroute from Tungpu to Hoshe, Huang 3443 (TNU); Wushe, elev. ca. 1100m, Peng 8344 (HAST).
Chiayi: Fenchihu-Tianchian, elev. ca. 1300-1405 m, Wang et al. 6243 (TNU, HAST), 6244 (TNU); same loc., Y. J. Chen & Shen 819 (TNU).
Pingtung: Wanluan District: Wanchin. In fallow field, elev. ca. 0 m, Peng & Chen 10150 (HAST).
Ilan: Nanshan, Kao 3130 (TAI); Mt. Taipei, Chuang et al. 4800 (TAI); Taipingshan, elev. ca. 1950 m, Peng 7868 (HAST); same loc., Y. J. Chen 857 (TNU).
Hualien: Karenko, Hosokawa s. n. Aug. 13, 1932 (TAI); Shoufeng District. Mt. Mukwashan Forest, Halun Station, elev. ca. 2000 m, Peng 7357 (HAST).
Canada, Northern USA, South-eastern USA, South-central USA, Italy, Central Europe, South-eastern Europe, USSR, China (Yunnan, Sichuan, Gansu), Japan, Korea. Taiwan, in open sunny places from 350-2400 m. Flowering in May.- Nov.
Hsu (1978) 描述本分類群花梗在苞片以上有分支，上分支皆著生雄花；但本研究發現並非所有上分支皆為雄性花，有些為兩性花，且可結飽滿的果實。
本種植物形態上和Co. diffusa極為相似，以營養器官幾乎無法區別兩者，但生殖器官的特徵則十分穩定且有用：本種植物苞片較大，寬心臟形，花大，有一枚花瓣較小，為白色，果實二室，每室二顆種子；Co. diffusa苞片較小，為狹長的心臟形，花較小，三枚花瓣皆為藍色，果實三室，其中一室不開裂，內含一顆種子。在海拔分布方面，本種植物主要分布在中海拔地區較高於Co. diffusa。
Phenology: annual herbs, evergreen
Roors form: roots fibrous
Stems form: monomorphic stem
Monomorphic stems habit: procumbent
Rooting at nodes or not: rooting at nodes
Lateral shoots: not perforating
Phyllotaxis: spiral phyllotaxis
Leaves: petiole: sessile, subpetiolate
Leaves: shape (if dimorphic leaves, selected by rosette leaves): lanceolate
Leaves: apex: acuminate
Leaves: length (cm): 5.5-8
Leaves: width (cm): 1.5-2
Leaves indumentum: upper surface: pubscent
Prophyll: sheathing, apex acute
Inflorescence: take plance: terminal
Inflorescence: cincinnus
Bracts: shape: spathe broadly cordate, folded
Corolla: zygomorphic: petal 3, base free, unequal
Flowers: bisexual
Sepals: sepal 3, unequal
Sepals: color: greenish
Sepals: base: the anticous 2, basally fused
Sepals: shape: the anticous 2 elliptic; the posticous one lanceolate
Sepals: indumentum: glabrous
Sepals: length (if dimorphic sepals, selected by anticous two) (mm): 4.5-5
Sepals: width (if dimorphic sepals, selected by anticous two) (mm): 3-3.7
Flowers: color: pink, purple, or blue
Petals: shape: dimorphic: the lateral petals 2 broadly ovate; the medial petal small
Petals: length (mm): 10
Petals: width (mm): 8-10
Stamens form: trimorphic: fertile stamens 3
Ovarys: shape: ellipsoid
Ovarys: indumentum: glabrous
Ovarys: length (mm): 2
Styles: indumentum: glabrous
Styles: length (mm): 1.3
Capsules: dehiscence: dehiscent
Capsules: shape: ellipsoid
Capsules: bilocular
Capsules: indumentum: glabrous
Capsule locules seeds: number: 2
Capsules: length (mm): 6-7
Seeds: lengh (if dimorphic seeds, selected by dorsal one) (mm): 2.5-3.5
Seeds: width (if dimorphic seeds, selected by dorsal one) (mm): 2.5
