346 



ARACEAE 



A 



1. Lysichiton camtschatensis (L.) Schott. 

 Yellow Skunk Cabbage. Fig 845. 



Dracontixim caintscJiatense L. Sp. PI. 968. 1753. 



Lysichiton camtschatensis Schott, Oestr. Bot. Wochenbl. 7: 62. 



1857. 

 Arctodracon camtschaticum A. Gray, Mem. Am. Acad. II. 6: 



408. 1858. 



Acaulesceiit ill-scented swamp-inhabitating herb, with 

 thick peppery rootstock. Leaves erect or ascending, 

 3-15 dm. tall, oblong-lanceolate, acutish, narrowed below 

 to a sessile base or a short petiole, rather thin, 

 glabrous ; spathe with a broad acute blade. 6-10 cm. 

 long, yellowish ; spadix 4-8 mm. long, greenish yellow, 

 on a stout peduncle becoming 3-5 dm. long. 



In swamps. Transition and Canadian Zones; Alaska to northern 

 Idaho, and in the Coast Ranges to the Santa Cruz Mountains, 

 California, also on the Pacific Coast of Asia to Japan. The pep- 

 pery roots are reputed to have medicinal value, and are used for 

 the treatment of such skin diseases as ringworm. Type locality: 

 .\sia. 



Zantedeschia aethiopica (L.) Sprang. {Richardia acthw['ica 

 Hort.) Common Calla. The common white calla of the gardens 

 is extensively cultivated, and especially in central and southern 

 California occasionally established in moist situations. Native ot 

 southern .Africa. 



Family 14. LEMNACEAE. 



Duckweed Family. 

 Minute stemless and leafless perennial plants, floating free on the surface of 

 fresh water. The plant body consisting of a disc-shaped, elongated or irregular 

 thallus, loosely cellular, rootless or bearing 1 or more simple rootlets. Inflorescence 

 composed of one or more naked monoecious flowers borne in a sac-like spathe on 

 the edge or upper surface of the frond. Flowers consisting of a single stamen or 

 a single flask-shaped ovary. Anther with 2 or 4 pollen-sacs ; pollen-grains bar- 

 bellate. Pistil narrowed to the funnel-shaped scar-like stigmatic apex, 1 -celled ; 

 ovules 1-6, erect or inverted. Fruit a 1-6-seeded utricle ; seeds large ; embryo 



straight 



A familv of 4 genera and about 26 mostly widely distributed species. The simplest and smallest of 

 flowering plants, propagating by the proliferous growth of a new individual froni a cleft m the edge or 

 base of the frond, also by autumnal fronds m the form of minute bull)lets which sink to the bottom 

 of the water, but arise and vegetate in spring. The flowers are scarce, in some species hardly ever seen. 



Rootlets present, 1 or more. 



Rootlets more than 1, fascicled. 



Rootlets 1. 

 Rootlets none. 



1. Spirodela. 



2. Lemna. 



i. Wolffiella. 



1. SPIRODELA Schleid. Linnaea 13: 391. 1839. 



Fronds disc-shaped, 7-12-nerved, the stipe attached to the frond back of and under the 

 basal margin. Rootlets several, fascicled, these and the nerves of the fronTi with a single 

 bundle of vascular tissue. Reproductive pouches 2, triangular, opening as clefts m either 

 margin of the basal portion of the frond. Spathe sac-like. Spadi.K of 1 pistillate and z 

 staminate flowers from the reproductive pouches. Filaments curving upward from the 

 margin of the frond ; anthers 2-celled. longitudinally dehiscent. Ovule 2. anatropous. Fruit 

 rounded wing-margined. [Greek, referring to the cluster of rootlets.] 



A genus of 3 species, two American and one Asiatic and Australian. Type species, Lcmna polyrhica L. 



1. Spirodela polyrhiza (L.) Schleid. 

 (Greater Duckweed. Fig. 846. 



Lcmiw t^ojyrliisa L. Sp. PI. 970. 1753. 



Stirodcla pulyrhiza Schleid. Linnaea 13: 392. 1839. 



Fronds solitary or united in colonies of 2-5, round- 

 obovate. 3-6 mm. long, flat and dark green on the 

 upper surface, slightlv convex and purplish beneath, 

 5-11-nerved; rootlets 5-11: rootcap large, sharp- 

 pointed ; spathe a complete sac. opening at the upper 

 end ; seed slightly compressed, smooth. 



In slow-running streams, ponds and shallow lakes, 

 widely distributed in the Old World and in North and 

 tropical America. On the Pacific Coast ranging from 

 British Columbia to southern California, but not common 

 in California. Tvpe locality: Europe. 



