TYPHACE^. (cat-tail FAMILY.) 467 



1. LEMNA, L. Duckweed. 



Spathes marginal, 3-flo\vered. Anthers opening transversely. Stigma 

 funnel-foim. Ovules erect from the base of the cell. — Stems increasing by 

 lateral buds. Hoots terminating in a calyptra-like appendage. — The flowers 

 of these plants are seldom seen. 



§ I. Root single : ovule solitary, half anatropous, or orlhotropous. — Lemna. 



1. L. trisulca, L. Frond thin, lanceolate-oblong, denticulate near the 

 apex, slender-stijjed, compoundly proliferous, mostly in threes, 1-nerved, 3"- 

 9" long ; seed half anatropous. — Mountains of North Carolina ? 



2. L. Valdiviana, Philippi. Fronds short-stiped, oblong, thin, faintly 

 1-nerved, conimoDly in groups of 4-8, r'-2" long ; utricle long-ovate, about 

 half as long as the frond, pointed by the long style ; seed orthotropous, apicu- 

 late; albumen scanty. — Ponds, etc., Florida, and northward. 



3. L. minor, L. Stems pale, round-obovate, flattened, single or variously 

 clustered ; root single ; ovule solitar}-, half auatropous ; seed horizontal. — 

 Pools, ditches, etc., Florida, and northward, probably intermixed with L. per- 

 pusilla, Torr. — Stems 1"- 2" long. 



§ 2. Roofs several, clustered : ovules 2, anatropous. — Spirodela. 



4. L. polyrhiza, L. Stems roundish or obovate, flat and pale above, 

 convex and dark purple beneath, clustered ; roots numerous, clustered ; ovules 

 2. — Ponds, Florida, and northward. — Less common than the preceding. 

 Stems 2" -4" long. 



2. WOLFFIA, Horkel. 



Spathe central, 2-flowered. Anther 1-celled, opening lengthwise. Stigma 

 depressed. Ovule oblique, orthotropous. Utricle globular. Albumen thin. 

 — ^Fronds M'ithout roots or nerves, coarsely cellular, proliferous. 



1 . W. Columbiana, Karsten. Very minute, roundish, lenticular, deep 

 green, with a thin appendage at the base. — Floating with Lemna on still 

 water. 



2. W. gladiata, Hegelm. Frond ribbon-shaped, curved or falcate, 

 gradually narrowed to the obtuse apex, thin and transparent, 2" -4" long, 

 J" wide. — Floating in dense mats in ponds. Cedar Keys, Florida. 



Order 139. TYPHACE^E. (Cat-tail Family.) 



Simple-stemmed marsh herbs, with elongated strap-shaped nerved 

 leaves, and monoecions flowers, on a globular or cylindrical spadix, 

 destitute of floral envelopes, but enveloped in copious pappus-like 

 hairs or scales. Spathe bract-like or none. Anthers single or 2 - 4 

 together, on long and slender filaments. Ovary 1-celled, with a single 

 suspended anatropous ovule. Style slender. Fruit nut-like. Em- 

 bryo straight in copious albumen. — Sterile spadix placed above the 

 fertile, continuous or distant. 



