264 Araceae; Lemnaceae 



cm. long, 5-12 cm. wide, purplish to green, navicular-hemi- blades narrowly ovate to narrowly ovate-oblong, 10-20 cm. 



spherical gradually acuminate; spadix ellipsoidal, about 2 cm. long, 7-12 cm. wide, obmse, cordate or nearly so, usually 



long, densely flowered; fruit ripening in summer of the same green, rarely variegated (forma variegata T. Koyama. Fuiri- 



year. Wet places; Hokkaido, Honshu (centr. and n. distr.). hime-zazen-so) ; flowering after the leaves; spathe broadly 



Amur, Sakhalin, and Ussuri. elliptic, tinged with dark brown-purple; fruit ripening the 



2. Symplocarpus nipponicus Makino. Spathyema nip- second spring. July. Wet places; Hokkaido, Honshu (Chij- 



ponica (Makino) Makino Hime-zazen-so. Resembles goku Distr. and eastw.) . n. Korea. 



No. 1 but smaller; leaves several, rather long-petioled, the 



9. ACORUS L. Shobu Zoku 



Perennials with decumbent, rather thick, aromatic, branching rhizomes; leaves tufted, linear, equitant, ensiform, not narrowed 

 below, sheathing and surrounding the neck of the rhizome at base; scapes radical, erect, elongate; spathe consisting of a leaf like 

 sessile bract subtending the spadix and apparently continuous with the stem or peduncle; spadix cylindrical without an ap- 

 pendage; flowers bisexual; perianth-segments 6, 2-ranked, small, thick, incurved and truncate at apex; stamens 6, the filaments 

 linear; ovary oblong, 2- or 3-locular, with several ovules in each locule; style very short, the stigma small; berries reddish, the 

 seeds few, oblong, with a fleshy endosperm. Two species in temperate and warmer parts of Eurasia and N. America. 



lA. Leaves with a distinct midrib; spadix 4-7 cm. long, 6-10 mm. thick; plant robust, large I. A. calamus 



IB. Leaves without a midrib; spadix 5-10 cm. long, 3-5 mm. thick; plant slightly smaller 2. A. gramineus 



1. Acorus calamus L. A. calamus var. angustatus Bess.; 2. Acorus gramineus Soland. Sekisho. Rhizomes 



A. spurius Schott; Orontium cochinchinense Lour.; A. cochin- creeping, 5-8 mm. in diameter, much branched; leaves deep 



chinensis (Lour.) Schott; A. asiaticus Nakai Shobu. Rhi- green, linear-ensiform, gradually narrowed to an acuminate 



zomes 8-12 mm. in diameter, creeping; leaves 50-80 cm. long, apex, 30-50 cm. long, 2-6 (rarely 8) mm. wide, shining, with- 



6-15 mm. wide, flat, acuminate, smooth, deep green, ensiform, out a midrib, smooth; peduncle 10-30 cm. long, compressed- 



with a prominent raised midrib, scarcely narrowed below, the triangular, 3-5 mm. wide; bract (spathe) leaflike, rather 



sheathes flattened laterally; peduncle leaflike, shorter than the short, 7-15 cm. long, 2-5 mm. wide, erect; spadix ascending 



leaves, slightly flattened; bract (spathe) leaflike, 20-40 cm. to nearly erect, narrowly cylindric, terete, 5-10 cm. long, 3-4 



long, 5-8 mm. wide; spadix sessile, terete, cylindric, densely mm. thick, densely flowered, yellow. Apr.-May. Com- 



flowered, 4-7 cm. long, 6-10 mm. thick, ascending, light yel- mon in wet places along streams and around ponds; Honshu, 



low; anthers light yellow, slightly longer than the perianth. Shikoku, Kyushu. Formosa, China, and India. 



^May-Aug. Shallow water along rivers; Hokkaido, Hon- Var. pusillus Engl. Arisugawa-zekisho, Korai-zekisho. 



shu, Shikoku, Kyushu. Siberia, e. Asia, N. America, and Smaller in all respects. Much-prized as an ornamental pot- 

 Europe (introduced) . plant, with numerous cultivars. Introduced from China. 



Fam. 45. LEMNACEAE Uki-kusa Ka Duckweed Family 



Minute, free-floating, aquatic, stemless herbs; plant body a green scalelike or leaflike "frond" solitary or few in a group, 

 with or without roots, new individuals produced from the lateral gemmae, or reproductive pouches, these overwintering in 

 cold areas at bottom of ponds or ditches; inflorescence, when present, of 1 to several unisexual flowers, each with a single stamen 



or pistil; ovules 1 to several, erect or pendulous. About 4 genera, with about 25 species, widespread in temperate and warm 



regions. 



lA. Fronds with 1 or more roots; flowers marginal. 



2A. Roots 2 to several; fronds 5- to 12-nerved 1. Spirodela 



2B. Roots single; fronds 1- to 5-nerved 2. Lemna 



IB. Fronds without roots, very minute; flowers on upper side of the frond at the center 3. Wolffia 



1. SPIRODELA Schleid. Uki-kusa Zoku 



Fronds flat, free-floating, 5- to 12-nerved; roots with a thin root-cap and a single vascular bundle; spathe saclike; anthers 2- 



locular; ovary with 2 anatropous ovules; fruit globose, winged on margin. About 3 species, widely distributed in warmer 



and tropical regions. 



lA. Roots about 10; fronds broadly obovate, producing winter buds in the form of bulblets 1.5. polyrhiza 



IB. Roots 3 to 5; fronds smaller, oblong to obovate, not forming the winter buds 2. 5. oligorrhiza 



1. Spirodela polyrhiza (L.) Schleid. Lemna polyrhiza surrounded by a small spathe; inflorescence composed of 3 



L. Uki-kusa. Fronds flat, broadly obovate, 5-8 mm. flowers, 2 staminate and 1 pistillate. Common in ditches, 



long, 4-6 mm. wide, rounded to a very obtuse apex, purplish ponds, and paddy fields; Hokkaido, Honshu, Shikoku, Kyu- 



below, with 6-11 descending roots 3-5 cm. long, palmately shu. Cosmopolitan. 



5- to 11-nerved, the lateral gemmae (daughter fronds) pro- 2. Spirodela oligorrhiza (Kurz) Hegelm. Lemna oli- 



duced from the edges near the attachment of the root; autum- gorrhiza Kurz; 5. m.elanorhiza F. Muell.; S. pleiorhiza F. 



nal fronds or winter buds orbicular, thickish; flowers globose, Muell. ex Kurz Shima-uki-kusa, Hime-uki-kusa. Fronds 



