DIOSCOREACEAE. 83 



Family 7. DIOSCOREACEAE Lindl. 



YAM FAMILY. 



Herbaceous or slightly woody twining vines with fleshy or woody 

 rootstocks, slender stems, petioled, mostly cordate, several-nerved and 

 reticulate-veined leaves, and small inconspicuous dioecious or monoecious 

 regular flowers in spikes, racemes or panicles. Perianth 6-parted, that of 

 the pistillate flowers persistent. Staminate flowers with G or 3 stamens, 

 sometimes with a rudimentary ovary. Pistillate flowers with an interior 

 3-celled ovary, 3 styles and 3 terminal stigmas, sometimes also with 3 or 6 

 staminodia; ovules 2 (rarely 1) in each cavity of the ovary, pendulous, 

 anatropous or amphitropous. Fruit a 3-valved, 3-angled capsule in the 

 following genus. Endosperm of the seed fleshy or cartilaginous, enclosing 

 the small embryo. About 9 genera and 175 species, mostly natives of 

 America, a few in the Old World. 



1. DIOSCOREA L. 



Characters of the family as defined above. [Name in honor of the Greek 

 naturalist Dioscorides.] About 160 species, most numerous in tropical regions, 

 a few in the temperate zones. Type species: Dioscorea saliva L. There are 

 no native nor naturalized species of the Yam Family in Bermuda. 



Dioscorea sativa L., one of the yams widely cultivated in tropical America, 

 has been grown locally, at times, but has not obtained any economic importance, 

 and it is not known to exist in Bermuda at present. It is a high-climbing 

 glabrous vine, with thin, slender-petioled, broadly ovate, deeply cordate 

 acuminate, palmately-veined leaves, minute, green flowers in long, clustered 

 spikes, and large underground edible tubers. [D. lutea of Jones.] 



Dioscorea bulbifera L., AIR POTATO, of tropical Asia, sometimes planted 

 for interest, has similar leaves and flowers, but has the peculiarity of producing 

 tubers in the leaf-axils. 



Family 8. IRIDACEAE Lindl. 

 IRIS FAMILY. 



Perennial herbs with narrow equitant 2-ranked leaves and perfect, 

 mostly clustered flowers subtended by bracts. Perianth of 6 segments or 

 6-lobed, its tube adnate to the ovary, the segments or lobes in two series, 

 convolute in the bud, withering-persistent. Stamens 3, inserted on the 

 perianth opposite its outer series of segments or lobes; filaments filiform, 

 distinct or united ; anthers 2-celled, extrorse. Ovary inferior, mostly 3- 

 celled; ovules mostly numerous in each cell, anatropous; style 3-cleft, its 

 branches sometimes divided. Capsule 3-celled, loeulicidally dehiscent, 3- 

 angled or 3-lobed (sometimes 6-lobed), many-seeded. Endosperm fleshy 

 or horny; embryo straight, small. About 57 genera and 1000 species, of 

 wide distribution. 



Perianth-segments separate, spreading. 1. Sisyrinchium. 



Perianth funnelform, 6-lobed. '2 



