SAXIFRAGE FAMILY 377 



Leaves of the caudex with lobed blades, the margins poreless. 



17. MUSCAKIA. 



Leaves of the caudex with serrate blades, each tooth with an encrusted 

 pore. 18. CnoNDROSEA. 



Hypanthiura only slightly developed, unchanged at maturity, or if slightly accres- 

 cent, then flat and plants acaulescent. 

 Leaves alternate, sometimes all basal. 

 Plants acaulescent. 



Corolla essentially regular, the petals about equal in shape and length. 



19. MiCRANTHES. 



Corolla irregular, except sometimes that of the terminal flower, 3 of the 

 petals with blades of an ovate or lanceolate type and 2 of them narrower 

 and longer. 20. Spatulaeia. 



Plants caulescent. 



Leaves without stipules. 



Carpels distinct; leaf-blades toothed. 21. Leptarrhena. 



Carpels partially united; leaf-blades entire or rarely with 3 apical tooth- 

 like lobes. 22. Leptasea. 

 Leaves with reniform or orbicular, shallowly lobed blades and wing-like 

 stipules at the base of the petioles. 23. Heterisia. 

 Leaves opposite, except sometimes on the flower-stalks. 24. Antiphylla. 



1. CHRYSOSPLENIUM (Toiirn.) L. Golden Saxifrage, 



Water Carpet. 



Low, somewhat succulent herbs, mainly semi-aquatic; all North American 

 species, with perennial rootstocks. Flowers small, axillary or terminal, solitary 

 or in small corymbs. Hypanthium saucer-shaped or campanulate, adnate to 

 the lower portion of the g^-noecium and usually lined with a disk. Sepals nor- 

 mally 4. Petals none. Stamens 4-8 (rarely 10), inserted on the margin of the 

 disk. Gynoecium 1-celled, 2-lobed; styles 2, usually short; placentae parietal, 

 many-ovuled. 



Leaves all alternate; flowers clustered near the ends of the stems; stamens 4. 



1. C. tetrandrum. 

 Lower leaves opposite; flowers solitary in the leaf-axils; stamens mostly 8. 



2. C. americanum. 



1. C. tetrandrum Th. Fries. Perennial, with a stoloniferous rootstock; 

 stem 1.5-8 cm. high; leaf-blades thick, reniform, 4-12 mm. wide, crenate with 

 3-5 broad teeth; sepals usually 4; stamens opposite to the sepals. Wet places, 

 arctic-alpine situations: Arctic coast — Colo. Subalp. Jl-S. 



2. C. americanum Schwein. Perennial, with a slender, stoloniferous root- 

 stock; stem decumbent, forked above, glabrous or nearly so, 7-20 cm. long; leaf- 

 blades broadly obovate, orbicular or rarelv reniform, 4-20 mm. wide. Wet 

 shady places: N.S. — Ga. — Minn. — Sask. Plain. Ap-Au. 



2. LITHOPHRAGMA Nutt. Star-flower, Prairie Star, 



Woodland Star. 



Perennial herbs, with slender bulblet-bearing rootstock and axial leafy 

 flowering shoots. Flowers racemose, perfect; hypanthium campanulate or 

 hemispheric and adnate to the very base of the ovary, to elongate-turbinate 

 and adnate to the lower half thereof. Sepals 5, valvate, rounded to triangular. 

 Petals white or rose-colored, clawed, digitately or pinnately divided, toothed, 

 or entire, much exceeding the sepals. Stamens 10, included; filaments short; 

 anther cordate. Gynoecium 1-celled with 3 parietal placentae, 3-valved at the 

 apex; styles 3, short. Seeds many. 



Hypanthium campanulate or hemispheric, mostly rounded at the base, adnate only to 

 the base of the ovary. 

 Stem-leaves seldom bulbiferous in the axils; stipules long and narrow, the free portion 

 triangular or lanceolate, not flmbriate. 

 Hypanthium with the sepals 2-3 mm. long; petals about 2 mm. long. 



Pedicels short, in fruit not exceeding the capsule in length; seeds smooth. 



1. L. tenella. 

 Pedicels in fruit much longer than the capsule; seeds muriculate. 



2. L. glabra. 

 Hypantliium with the sepals 3— t mm. long; petals 3-5 mm. long. 



3. L. australis. 

 Stem-leaves usually bulbiferous in their axils; stipules short and broad, the free portion 



rounded and flmbriate. 4. L. bulbifera. 



Hypanthium deeply obconic, adnate to the lower half of the ovary. 5. L. parviflora. 



Itj* 



