ORDER CXL. RESTIACE2E. 553 



I. C. flex'ilis, (Willd.) Stem slender, glabrous, submersed, branch- 

 ing. Leaves verticillate, in a whorl, linear, denticulate at the summit. 

 Flowers solitary, axillary, sessile. — If. May — July. Stagnant waters. 

 2—3 feet. 



Genus III.— RUP'PIA. L. 4—4. 



(In honor of H. B. Ruppius, of Gottingen.) 



Flowers perfect, on a spadix, arising- from the base of the 

 leaves. Statnens sessile. Stigmas 4. Ovaries 4. Perianth 

 none. Fruit pedicellate, consisting of four 1-seeded drupes. 



1. R. mabiti'ma, (L.) Stem floating, glabrous. Leaves filiform, with 

 inflated sheaths. Peduncles axillary, somewhat spiral, bearing 2 naked 

 green flowers. Anthers 4, sessile. — 2£. July. Salt marshes. 



Genus IV.— POTAMOGE'TON. L. 4—3. 



(From potamos, a river, and geton, near.) 



Flowers perfect, on a spadix arising from the spathe. Peri- 

 anth 4-leaved. Anthers 4, sessile, alternating with the leaves 

 of the perianth. Nuts 4, 1-seeded, sessile. 



1. P. flu'itans, (L.) Stem branching, glabrous. Leaves floating, on 

 long petioles, sub-coriaceous, oval-lanceolate ; the lower ones narrow, 

 sessile, long. Flowers in axillary spikes, almost submersed. — 2£. May 

 — June. Stagnant waters. 2 — 6 feet. 



2. P. heterophyl'lum, (L.) Stem branching, glabrous ; upper leaves 

 opposite, lanceolate, 5-nerved, lower ones linear, sessile. Flowers 

 crowded on the spadix. — If. July — Aug. Stagnant waters. 



3. P. pauciflo'rum, (Pursh.) Stem branching, diffuse. Leaves linear, 

 sessile ; the upper verticillate, the lower alternate. Spadix 1 from 

 each whorl of leaves, bearing 4 — 10 flowers. — If. Through the sum- 

 mer. Shallow water. 



4. P. lu'cens, (L.) Stem long, branched. Leaves submersed, elliptic 

 and elliptic-lanceolate, large, pellucid, veined. Spadix cylindric, many- 

 flowered. Peduncle thickened above, varying in length. Fruit com- 

 pressed, obtusely angled, slightly keeled. — U. July — Aug. Carolina 

 to Canada. 



Order CXL.— RESTIA'CE^E. (Cord-rush Family.) 



Flowers monoecious. Perianth 4-parted. Stamens 4 — 6, 

 attached to the perianth. Ovary 2 — 3-lobed, 2 — 3-celled, with 

 a solitary, pendulous ovule in each cell. Fruit capsular. Her- 

 baceous plants, with stems naked, or bearing leaves. Flowers 

 in terminal heads, separated by bracts. 



Genus I.— ERIOCAU'LON. L. 3—3. 

 (From erion, wool, and canton, a stem.) 



Flowers monoecious ; sterile florets occupying the center of 

 the capitulum. Stamens 4 — 6. Perianth 4-parted, the 2 in- 



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