STONE-CROP FAMILY 375 



6. TILLAEASTRUM Britton. 



Small glabrous aquatic annuals. Leaves opposite, entire. Flowers perfect, 

 small, solitary, axillary. Sepals 4, distinct. Petals usually 4, distinct or united 

 at the base. Stamens 4. Carpels 4, distinct, several-seeded; styles short. 



1. T. aquaticum (L.) Britton. Stem 1-8 cm. high; leaves linear-oblong, 

 connate at the base, 4-6 mm. long; flowers subsessile; petals greenish, about 

 twice as long as the sepals; follicles ovoid, 8-10-seeded. Tillaea aquatica L. In 

 mud or water: N.S. Md. -La. Tex. L. Calif. Wash.; Eurasia. Plain 

 Mont. 



FAMILY 56. PARNASSIACEAE. GRASS OF PARNASSUS FAMILY. 



Scapose perennials, with rootstocks and basal petioled entire leaves. 

 Flowers solitary on the scape, perfect, regular. Sepals 5, imbricate. Petals 

 5, imbricate, white or nearly so, conspicuously veined. Stamens 5, alternate 

 with the petals and with 5 clusters of united gland-tipped staminodia. 

 Gynoecium of 3 or 4 united carpels; ovary superior or half inferior, with 3 

 or 4 parietal placentae; style obsolete; stigmas 3 or 4. Fruit a 1-celled cap- 

 sule, loculicidal at the apex. 



1. PARNASSIA. GRASS OF PARNASSUS. 

 Characters of the family. 



Petals fimbriate on the sides, at least below; free portions of the staminodia very short 



and stout; leaf-blades reniform or cordate, usually broader than long. 

 Petals obovate, 5-nerved; staminodial scales with 59 lobes; sepals elliptic. 



1. P. fimbriata. 

 Petals oblong, 3-nerved; staminodial scales with 3-5 lobes; sepals narrowly lanceolate. 



\ 2. P. rivularis. 



Petals entire, not flmbriate; free portion of the staminodia long. 



Petals 5 9- veined, usually exceeding the sepals; capsule less than twice as long as 



the sepals; bract some distance from the base. 

 Staminodia 7-15 in each fascicle; basal leaf-blades cordate or rounded at the 



base. 



Petals nearly twice as long as the sepals; hypanthium inconspicuous ; stamin- 

 odia usually 9-15 in each fascicle. 3. P. palustris. 

 Petals only slightly exceeding the sepals; hypanthium conspicuous, obconic, 

 fully half as long as the sepals and nearly as broad as high; staminodia 

 7-9 in each fascicle. 4. P. montanensis. 

 Staminodia 5-7 in each fascicle; basal leaf-blades acute at the base. 



5. P. parviflora. 



Petals 3-veined, thin, scarcely equalling the sepals ; capsule twice as long as the sepals ; 

 bract none or near the base. 6. P. Kotzebuei. 



1. P. fimbriata Konig. Leaf -blades reniform or broadly cordate, 2-4 cm. 

 wide, thin; scape 2-3 dm. high; sepals 5-6 mm. long, elliptic or oval, obtuse, and 

 often crenulate at the apex; petals obovate, 7-8 mm. long; capsule 1 cm. long or 

 more. Springy places in the mountains: Alta. Colo. Calif. Alaska. Mont. 

 Subalv. Jl-S. 



2. P. rivularis G. E. Osterhout. Leaf-blades reniform or broadly cordate, 

 thin, about 7-ribbed, 1-2 cm. wide; scape slender, about 1 dm. high; sepals 

 narrowly lanceolate, acute, about 3 mm. long; petals oblong, about 6 mm. long; 

 capsule ovoid. Springy places in the mountains: n Colo. Mont. 



3. P. palustris L. Leaf-blades cordate, 1-3 cm. wide; scape 1-3 dm. high; 

 sepals oblong or elliptic, 4-6 mm. long; petals oval, 8-12 mm. long; capsule 

 ovoid, about 1 cm. long. Wet places: Lab. Que. Mich. -Wyo. Alaska; 

 Eurasia. Mont. Jl-Au. 



4. P. montanensis Fern. & Rydb. Leaf-blades ovate, with a subcordate 

 or rounded base, 1-2 cm. long, 8-18 mm. wide; scape about 2 dm. high; sepals 

 oblong to lanceolate, acute, 7-9 mm. long; petals oval to elliptic; capsule rounded- 

 ovoid, about 1 cm. long. Wet river banks: Mont. B.C. Sask. Submont. 

 Mont. Jl-Au. 



5. P. parviflora DC. Leaf-blades oval or ovate, 1-3 cm. long, 0.75-2 cm. 

 wide; scape slender, 1-3 dm. high; sepals oblong, 5-8 mm. long; petals elliptic 



