TYPHACE.E. (CAT-TAIL FAMILY.) 467 



1. LEMNA, L. DUCKWEED. 



Spathes marginal, 3-flowered. Anthers opening transversely. Stigma 

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

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

 of these plants are seldom seen. 



1. Root single : ovule solitary, half anatropous, or orlhutropous. LEMNA. 



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

 apex, slender-stiped, 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, tliiu, faintly 

 1 -nerved, commonly in groups of 4-8, l"-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 solitary, half anatropous; seed horizontal 

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

 pusilla, Ton-. Stems \" - 2" long. 



2. Roots several, clustered : ovules 2, anatropous. SPIRODELA. 



4. L. polyrhiza, r>. 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 without 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, 

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



ORDER 139. TYPHACEJE. (CAT-TAIL FAMILY.) 



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

 leaves, and monoecious 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. 



