302 ORDER 119. EMPETRACE^E. 



* Stems Bhort (6"- 20, spreading on moist grounds. Leaves reniform Nos. 1. 2 



* Stems (316') growing in water. Fruit sessile. a; Leaves of two kinds. . .Nos. 3, 4 



x Leaves all linear No. 5 



1 C. Austin!! Eng. Lvs. obovate, 1 2" ; fruit depressed, 4-lobed all around, its pedi- 



cel and stig. nearly as long, lobes narrowly winged. N. J. (Porter), N. Y., and W. 



2 C. peploideg N. Lvs. elliptical, 1" ; fruit roundish, 4-lobed above, sessile, its stig- 



mas twice as long, lobes not winged. Tenn. to La. (Hale). 12'. 



3 C. verna L. Floating Ivs. 3", rosulate, obovate, narrowed below, the submersed 



leaves 6", oblong-linear; fruit oval, emarginate, longer than its stigmas. Pools. 



4 . heterophf lla Ph. Floating leaves spatulate, attenuate below, 46", the sub- 



mersed linear, 6 9"; fruit globous, obcordate, its stigmas rather longer. Pools. 

 6 C. autumnalis L. Leaves all submersed, 35". linear, obtuse at both ends ; fruit 

 rounded, its lobes slightly united, winged ; styles slender. Lakes and rivers. 



ORDER CXVIL PODOSTEMLACE^E. THREADFOOTS. 



Serbs aquatic, with the habit of seaweeds, with alternate, dissected 

 leaves, with flowers minute, perfect, naked or with 3 sepals. Stamens 1 or 

 many, hypogynous. Ovary compound, 2-3-celled, with as many stigmas, 

 and numerous ovules. Fruit a many-seeded capsule, ribbed and some- 

 what pedicelled. Albumen none. 



PODOSTEMUM, L. C. Rich. THREADFOOT. RIVER WEED. Fls. 

 axillary, solitary. Sta. 2, fil. united below. Ovary oblong-ovoid. Stig. 2, 

 sessile, recurved. Caps. 2-celled. Seeds minute. Small, submersed ^r, 

 adhering to stones and pebbles. 



P. ceratophyllum MX. Leaves alternate, repeatedly forking into linear, thread- 

 form segments ; stem a few inches long, in running water : common. 



ORDER CXVIII. CERATOPHYLLACEJ3. HORNWORTS. 



Herbs aquatic, with whorled, dichotomously dissected leaves. Flowers 

 8 , sessile, axillary, minute, with neither calyx nor corolla. Involucre 8- 

 12-cleft. AntTiers (1224) sessile. Fertile flower a simple 1-celled ovary 

 with one ovule. Cotyledons 4. 



CERATOPHYLLUM, L. HORNWORT. Character that of the order, x? 

 fj. deniersum L. Stem floating or prostrate, 816', with numerous branches and 

 whorls ; leaf-segment filiform, sharply toothed. Pools. 



ORDER CXIX. EMPETRACE^E. CROWBERRIES. 



Heath-like shrubs, with evergreen, linear, exstipulate leaves, and small, 

 imperfect flowers. Calyx of 4 6 hypogynous, imbricated scales, the inner 

 often colored and petal-like. Stamens 24, with compound pollen. Ovary 

 free, 2-9-celled, 2-9-ovuled. Fruit fleshy, with as many seeds. In Balis 

 the drupes are consolidated. 



StamensS. Stigmas 6-9-rayed. Berry 6-9-seeded EMPETRU*. 1 



Stamns3. Stigmas 3 or 4. Style slender. Drupe 3- or 4-seeded OOREMA. 2 



Stamens2. Stigmas 4. Berry 2-seeded. Shrub erect CERATIOLA. 3 



itamensi Stigmal. Berry 4-seeded. Prostrate BAIIS. 4 



