Genus i. 



SPIDERWORT FAMILY. 



457 



Family 18. COMMELINACEAE Reichenb. Consp. 57. 1828. 



Spiderwort Family. 

 Perennial or annual leafy herbs with regular or irregular perfect and often 

 showy flowers in cymes, commonly subtended by spathe-like or leafy bracts. 

 Perianth of 2 series; a calyx of mostly 3 persistent sepals, and a corolla of mostly 

 3 membranous and deciduous or fugacious petals. Stamens mostly 6, hypogy- 

 nous, rarely fewer, all similar and perfect or 2 or 3 of them different from the 

 others and sterile ; filaments filiform or somewhat flattened ; anthers 2-celled, 

 mostly longitudinally dehiscent. Ovary superior, sessile or very nearly so, 

 2-3-celled ; ovules 1 or several in each cell, anatropous or half anatropous ; style 

 simple ; stigmas terminal, entire or obscurely 2-3-lobed. Seeds solitary or several 

 in each cell of the capsule. Capsule 2-3-celled, loculicidally 2-3-valved. Embryo 

 small. Endosperm copious. 



About 25 genera and 350 species, mostly natives of tropical regions, a few in the temperate 



zones. 



Perfect stamens 3, rarely 2 ; petals unequal ; bracts spathe-like. 1. Commelina. 



Perfect stamens 6, rarely 5 ; petals all alike ; bracts leafy or minute. 



Cymes or cymules subtended by small minute bracts. 2. Cuthbertia. ' 



Cymes or cymules subtended by leaf-like bracts. 3. Tradescantia. 



i. COMMELINA L. Sp. PI. 40. 1753. 

 Erect ascending or procumbent, somewhat succulent, branching herbs, with short-peti- 

 oled or sessile leaves, and irregular mostly blue flowers in sessile cymes subtended by 

 spathe-like bracts. Sepals somewhat unequal, the larger ones sometimes slightly united. 

 Petals blue, unequal, 2 of them larger than the third. Perfect stamens 3, rarely 2, one of 

 them incurved and its anther commonly larger. Sterile stamens usually 3, smaller, their 

 anthers various. Filaments all glabrous. Capsule 2-3-cclled. Seeds 1 or 2 in each cavity, 

 the testa firm, roughened, smooth or reticulated. [Dedicated to Kaspar Commelin, 1667- 

 1731, Dutch botanist.] 



About 95 species of wide distribution in warm and temperate "regions. Besides the following, 

 some 3 others occur in the southern United States. Type species : Commelina communis L. 

 Spathes not united at the base. 



Spathes acuminate ; capsules 3-celled, 5-seeded. 1. 



Spathes acute ; capsules 2-celled, 4-seeded. 

 Spathes with united bases. 



All three cavities of the ovary with 2 ovules. 



Sheaths, at least the lower ones, glabrous or nearly so ; pubescence, if present, not hirsute. 



3. C. crispa. 

 Sheaths more or less hirsute. 



Capsules 2-valved, dorsal cavity indehiscent. 4. C. virginica. 



Capsules 3-valved, all cavities dehiscent. 5. C. erecta. 



Ventral cavities of the ovary with 2 ovules, dorsal cavity with 1 ovule. 6. C. hirtella. 



i. Commelina nudiflora L. Creeping 

 Day-flower. Fig. 1147. 



Commelina nudiflora L. Sp. PI. 41. 1753. 

 Commelina caroliniana Walt. Fl. Car. 68. 1788. 

 Commelina agraria Kunth. Enum. 4 : 38. 1843. 



Glabrous or very nearly so throughout, 

 stems procumbent or creeping, rooting at the 

 nodes, i°-2i° long. Leaves lanceolate or 

 ovate-lanceolate, i'-3' long, 4"-%" wide, acute 

 or acuminate at the apex, their sheaths some- 

 times ciliate ; spathe acute or acuminate, 8"-i2" 

 long, peduncled, the 2 bracts not united by 

 their margins; flowers few in each spathe, 

 3" -6" broad; ventral cells of the ovary 

 2-ovuled, the dorsal i-ovuled ; capsule com- 

 monly 5-seeded (2 seeds in each of the ventral 

 cells, 1 in the dorsal) ; seeds oblong, reticu- 

 lated, about 1" long. 



Along streams and in waste places, New Jersey 

 to Indiana, Missouri, Florida, Texas and through 

 tropical America to Paraguay. Widely distributed 

 in Asia and Africa. July-Oct. 



C. nudiflora. 

 C. communis. 



