Commelina nudiflora auct. non Linn. (1753): Henry, List Pl. Formos.. 98. 1896; Brown, J. Linn. Soc. Bot. 36: 156. 1903.
Perennial herbs. Roots fibrous. Stems branched, prostrate at base, erect above, rooting at node, puberulent along a line decurrent from the sheath, other glabrous. Leaves sessile-subpetiolate; blade lanceolate, 4-10 cm long, 0.9-2 cm wide, apex acuminate, base oblique, glabrous, scabrescent at margins; sheath cylindrical, with red stripes, pilose at margins. Prophyll ca. 2.5 cm long, diam. 3 mm. Inflorescences terminal Inflorescences terminal, upper cincinnus with 1-3 enserted male flower; lower cincinnus with 2-5 flowers; some flowering shoots branch from the prostrate stems; spathes, lanceolate, folded, ca. 1.4-4 cm long, 1.2-2.2 cm wide, apex acuminate, base cordate, veinlets inconspicuous, glabrous, margins scabrescent; the spathes of the lower flowering shoots shorter, ca. 0.5-0.9 cm long, ca. 0.6-0.8 cm wide; peduncles 0.5-2.6 cm long; pedicels ca. 3-5 mm long. Flowers zygomorphic, dimorphic: in functionally male flowers pistil abortive and usually lacking or vestigial; in bisexual flowers the pistis ca. 6 mm long; sepals 3, greenish, persistent, elliptic, concave, unequal, the anticous 2, basally fused, elliptic, the margins sometimes blue and petaloid, ca. 3.1 mm long, ca. 1.5 mm wide, glabrous; the posticous one lanceolate, ca. 3.5 mm long, ca. 2.8 mm wide; petals 3, free, unequal, the lateral petals 2, indigo, sometimes white, equal, planar, clawed, the limb broadly rounded-ovate, ca. 4.7 mm long, 7.4 mm wide, apex obtuse, base cuneate-cordate, the claw ca. 3 mm long; the medial petal blue, clawed, ca. 4.4 mm long, ca. 5 mm wide; fertile stamens 3, anticous, base fused, unequal, the lateral two, anther white or indigo, elliptic, base sagittate, ca. 1 mm long, filament ca. 4 mm long; the medial one, anther elliptic, base hastate, ca 1.5 mm long, filament ca. 3.5 mm long; staminodes 3, posticous, subequal, the medial staminode antesepalous, usually lacking or vestigial, the lateral ones antepetalous, antherodes cruciate, yellow or white, ca. 0.5 mm long, filament ca. 3 mm long, sometimes with 2 lateral abortive pollen sacks; ovary ellipsoid-globose, ca. 2 mm long; style ca. 4 mm long,. Capsules trilocular, 2-valved, brown, ellipsoid to globose, 6-9 mm long, ca. 3 mm wide, the ventral locule 2-seeded, dehiscent, the dorsal locule 1-seeded, indehiscent, glabrous. Seeds dimorphic: one in dorsal locule, light brown, elliptic in outline, ca. 3 mm long, 1.6-1.9 mm across; two in ventral, black, deltoid in outline, ca. 2 mm long, ca. 1.3 mm across, dorsiventral, ventral surface planar, dorsal convex, reticulate, densely covered with small farinose granules. Chromosome number: n =15.
Taipei: Chingmei District: a hiking trial of Hsienchiyen (stone), Y. J. Chen 427 (TNU); Chungho, Hsu 141 (TAI); Hsiaokaotou, Teng 1367 (TAI); Hsinpeitou, Kueitzukeng. Y. J. Chen & Wang 877 (TNU); en route from Hwakang to Tienmu, Peng & Tsai 6800 (HAST); Juifang: along the beach road from Hoping to Pitouchiao, elev. ca. 0-30 m, Leu et al. 331 (HAST); en route from Juifang to Chiufen, Y. J. Chen et al 299, 303 (TNU); Juifang Town: en route from Houtung to Mutan, Y. J. Chen et al 297 (TNU); Juifang Town: Houtung Y. J. Chen et al. 295 (TNU); Juifang Town: Szuchiaoting, Shen 214 (TNU); Keelung, Yamamoto s. n. 1931 (TAI); Keelung City: Hopingdao, Y. J. Chen & Wang 883 (TNU); Kelung City: water sheld of Nuannuan dam, Y. J. Chen et al. 524 (TNU); Keelung, Pengchiayu, elev. ca. 0-150 m, Huang et al. 15728 (TAI); same loc., (Agincort), Yamamoto et al. s. n. Aug. 15, 1933 (TAI); insl. Kizan, Masamune & Lnzuki s. n. Jul. 3, 1932 (TAI); Mt. Kuanyinshan, Peng 6035 (HAST); Kungliao to Tali (Ilan Hsien), Y. J. Chen 442 (TNU); same loc., Y. J. Chen & Wang 906 (TNU); Kueishan: Shihtien City, Chinese Culture Univ. Hua-Lin experiment forest, Y. J. Chen & Shen 865 (TNU); Kueishan to Bishantsuen, on the way to Feitsueiku, along Peishichi., Peng 4670 (HAST); Lelekuo, Shih 1986 (TAIF); Matsao, Peng & Yang 1679 (TAI); Nankang: campus of Academia Sinica. On lawn, elev. ca. 50 m, Wang & Hsu 731 (HAST); Peitou District: Kuantu temple, Y. J. Chen & Wang 879 (TNU); Peitou District: Hsinpeitou, Huanghsi Park, Y. J. Chen & Wang 903 (TNU); Pinglin: Huangchupiliao, Y. J. Chen et al 278 (TNU); Pinghsi Hsiang: Hsien Road #106, at mileage sign 77 km, en route from Shihfenliao to Juifang, elev. ca. 200-300 m, Hsiao et al. 1307 (HAST); Pinghsi, Shen 247 (TNU); Pinglin, Provincial Rd. #9 (Ilan to Taipei), Y. J. Chen & Wang 895 (TNU); Shihmen, Yang 2557 (TAI); Shihting District: en route to Mt. Huangtitienshan. In drainage ditch, elev. ca. 440 m, Peng 8552 (HAST); Shiting, Huang-ti-dien, Peng 5004 (HAST); same loc., Y. J. Chen & Wang 907 (TNU); Shulin Town: Kanyuan Bridge, Y. J. Chen & Wang 880 (TNU); Suigenchi, s. coll. s. n. Jul. 11, 1922 (TAI); Supai, Huang 2326 (TAI); Tansui Town: Hsiaopingting, Y. J. Chen & Wang 878 (TNU); Wanten, Simizu 3321 (TAI); Yangmingshan, Chienshan Park. In tree shade, elev. ca. 420 m, Peng & Leu 13511 (HAST); Yangmingshan National Park: Tatunshan, en route from Parking Lot of The Tatun Nature Park to Erhtzuping, elev. ca. 825-840 m, Y. J. Chen & Huang 244 (TNU); Yangmingshan. Matsao, Cut-over and weedy places, elev. ca. 600-650 m, Peng & Yang 8641 (HAST); Wulai, Y. J. Chen & Chen 433 (TNU); Wulai: Tunghou, en route from Mountain control station to guest house. Broadleaf forest. Moist pebbly streamside, elev. ca. 400 m, Liao et al. 421 (HAST,TNU); Wulai: Hsiaoyi to Tunghou, elev. ca. 200-300 m, Chen & Hsu 86 (TNU).
Taoyuan: Provincial road #7, Chilan, elev.ca. 400-500 m, Wang 10522 (TNU); Provincial road #7, Mileage sign from 75.5 km to 76.5km, Lunpei, elev. ca. 1000-1100 m, Wang 10571 (TNU); Lungtan. Y. J. Chen & Wang 864 (TNU); Yang-mei: Er-chung-his, elev. ca. 100 m, Wang 10219 (TNU); Yangmei. Y. J. Chen 843 (TNU).
Hsinchu: Hukou Hsiang: Hukou, Y. J. Chen & Chiu 901 (TNU); Kuanhsi Town. Wang et al. 10316 (TNU).
Miaoli: Yuanli, Jeng 481 (TAI).
Taichung: Pahsienshan Forest Recreation Area, Wang 10219 (TNU); Takeng, Ho 551 (TAIF); en route from Chunghsing Ling to Takeng (via Toukeshan Mt. ridge). Along roadside fence, elev. ca. 570 m, Peng 9979 (HAST).
Nantou: Chichi, Moo 2104 (TAI); Lienhwachih Y. J. Chen & Hsu 733 (TNU); Luku Hsiang: Fenghuangku. On the way from Fenghuang Hostel to Fenghuang Waterfall. Secondary broadleaf forest, elev. ca. 600-800 m, Wang et al. 120 (HAST); Mukaiyama Rinryu, Kudo & Sasaki s. n. Sep. 23, 1929 (TAI); inbula Shushi in Nichigetsutan, Kudo & Sasaki 15535 (TAI); Tungpu to Hoshe. Huang 3444 (TNU).
Yunlin: Touliu City: lane 39, Chen-Tung Rd., Y. J. Chen & Huang 871 (TNU).
Chiayi: Just off the Provincial Highway No. 1, on the way to Beigang Town. Along roadside drainage ditch, Peng 6006 (HAST); Budai Town: Hsinwen. Around a coastal pond, Peng 10081 (HAST); Chiayi City: campus of Chiayi Institute of Technology, Y. J. Chen & Chen 904 (TNU); Chuch District: Kwanghua Village, elev. ca. 1000 m, Peng 9945 (HAST); Min-hsiung Hsiang: Chen-tso-liao, elev. ca. 100 m, Wang & Yang 7986 (TNU); Tapu Hsiang: Watershed area of Tsengwen Dam, along a trail from bridge #4, Y. J. Chen et al. 805, 809 (TNU); Tungshih Hsiang, Aoku Village, along Provincinal Road #17, by Peikang River, elev. ca. 0 m, Peng et al. 13466 (HAST).
Tainan: Tungshan District, Mt. Chingshan, Hiking entrance of Hsienkungmiao, elev. ca. 100 m, Peng 7060 (HAST).
Kaohsiung: Liukuei to Meinung, Hsien Rd. #184, between Liukuei tunnel #2 and #3, Y. J. Chen et al. 791 (TNU); Shanping. Summer Collection Team. Jul, 1986 (TNU).
Pingtung: Chechung Hsiang: Szuchunghsi, elev. ca. 30 m, Peng 6811 (HAST); ChiuPeng. Y. J. Chen et al. 856 (TNU); Henchun to Tapanliah, Yamamoto s. n. Aug.-Sep. 1925 (TAI); Litingshan, Y. J. Chen & Huang 775 (TNU); Neipu Hsiang: Chiayi Primary School. Dry roadside in an Orchard, elev. ca. 0-50 m, Lin et al. 484 (HAST); en route from Kengting to Kuanshan, elev. ca. 50-80 m, Peng 12515 (HAST); Kenting National Park: Nanjenshan, elev. ca. 200-400 m, Peng 5551 (HAST); Nanjenshan, Chang 2106 (TAI); Man-Chou Hsiang: Laofoshan, elev. ca. 400-500 m, Lin 289 (HAST); Man-Chou Hsiang: Lanjenhsi, Y. J. Chen et al. 848 (TNU); Santi District: Santi, elev. ca. 200 m, Peng 10245 (HAST); Tungyuan, elev. 300 m, Y. J. Chen et al. 854 (TNU); Wutai Hsiang: on the way from Haocha to Old Haocha. Disturbed broadleaf forest, elev. ca. 250-430 m, Liu et al. 760 (HAST).
Ilan: Chiaohsi Hsiang: Chiaohsi, Y. J. Chen & Wang 872 (TNU); Chiaohsi Hsiang: seashore of Chu-An, No. 276 Chu-An Rd., Y. J. Chen & Wang 873 (TNU); Insl. Kizan, Taihoku, Masamune & Suzuki s. n. Jul. 3, 1932 (TAI); Wuweikung. Y. J. Chen 441 (TNU); Sanhsing, Yamamoto 3709 (TAI); Tali, Hsu 9294 (TAI); Yuanshan Hsiang: Shuanglienpei (pound.), elev. ca. 550 m, Y. J. Chen et al. 894 (TNU).
Hualien: Hungyeh, elev. ca. 200 m, s. coll. s. n. Jul. 3, 1988 (TNU); Huanlienhsi, Shen 225 (TNU); Liyutan (a lake near Huanlien City), Y. J. Chen & Shen 436 (TNU); Mataian, Kwarenko, Suzuki s. n. Oct. 16, 1934 (TAI).
Taitung: Lanyu (Orchid Island), between Kaiyuan Port & Airport, elev. ca. 10 m, Peng 7654 (HAST); Lanyu: Lantao Village, Lu 25242 (TAIF); Lanyu: Tungching Village, Y. J. Chen & Wang 881 (TNU); Between Hongtou Village and Yuzen Village roadside, by a ditch, Peng 5274 (HAST); Hungtou to Wangnanchao, Botel Tobago, Hsu 4852 (TAI); Kashoto, Kudo & Mori 178 (TAI); Kotosho (Lanhsu), Sasaki s. n. May. 5, 1924 (TAI).
South-eastern USA, South-central USA, Mexico, Central America, Colombia, Venezuela, Bolivia, Peru, Brazil, Paraguay, Argentina, Uruguay, Chile, Southern Africa, Eastern Africa, Central Africa, Western Africa, USSR, Middle East, Indian subcontinent, SE Asian subcont, China (Xizang, Yunnan, Guizhou, Guangxi, Guangdong, Nainan), Japan, Korea, Philippines, Indonesia, Australia, Pacific Islands. Taiwan, in waste places from 0-1100 m throughout the island. Flowering all the year round.
Morton (1956a, 1967) 研究西非的本種植物時，依據形態及染色體上的變異提出兩個亞種的階級：Co. diffusa subsp. aquatica及Co. diffusa subsp. montana。並認為Co. diffusa subsp. aquatica是一個局部分布的種類，多生長在沼澤，莖長且匍匐蔓延，葉為狹披針形，著生雄花的花梗明顯伸出苞片之外，苞片大，較Co. diffusa subsp. diffusa窄且長，染色體2n = 28；Co. diffusa subsp. montana分布在山區，和Co. diffusa subsp. aquatica同樣具有長梗且花大，但莖為短距離匍匐，葉子較小，卵形，苞片小，葉、葉鞘、苞片及花梗被有軟而透明的毛，染色體2n = 56, 60，是一個四倍體的種類；Co. diffusa subsp. diffusa和這兩亞種的最大區別在於植株小，花梗短，葉子為卵形-披針形。Umoh (1990) 依據Morton (1967) 的形態分類從事細胞學的研究，結果顯示這三個分類群染色體皆為2n = 30，並無染色體數目的差異。本研究發現上述營養器官的變異存在於族群間及族群內，和棲地有很大的關係，為不穩定的特徵，再加上細胞學的結果也不能反應形態上的變異，本研究認為應將這些亞種予以合併。
Hsu (1978) 描述本分類群花梗在苞片以上有分支，上分支皆著生雄性花；但在本研究所觀察的族群中發現上分支著生1-3朵花，但不全為雄性花。本種植物除了枝端長花序外，在植株下方的葉腋常會長出短小的花莖 (flowering shoots) 上有1-2枚鞘狀的葉子，花序長在花莖的頂端，其苞片及花通常較小，但並非閉鎖花。
Phenology: perennial 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): 4-10
Leaves: width (cm): 0.9-2
Leaves indumentum: upper surface: glabrous
If upper surface glabrous, leaves indumentum: margin: pubscent
Prophyll: sheathing, apex acute
Inflorescence: take plance: terminal
Inflorescence: cincinnus
Bracts: shape: spathe lanceolate, folded
Corolla: zygomorphic: petal 3, base free, unequal
Flowers: bisexual, functionally male flowers
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): 3.1
Sepals: width (if dimorphic sepals, selected by anticous two) (mm): 1.5
Flowers: color: white, pink, purple, or blue
Petals: shape: dimorphic: the lateral petals 2 broadly rounded-ovate; the medial petal small
Petals: length (mm): 4.7
Petals: width (mm): 7.4
Stamens form: trimorphic: fertile stamens 3
Ovarys: shape: ellipsoid-globose
Ovarys: indumentum: glabrous
Ovarys: length (mm): 2
Styles: indumentum: glabrous
Styles: length (mm): 4
Capsules: dehiscence: dehiscent, the dorsal locule usually indehiscent
Capsules: shape: ellipsoid, globose
Capsules: trilocular
Capsules: indumentum: glabrous
Capsule locules seeds: number: 1-2
Capsules: length (mm): 6-9
Seeds: lengh (if dimorphic seeds, selected by dorsal one) (mm): 3
Seeds: width (if dimorphic seeds, selected by dorsal one) (mm): 1.6-1.9
