Lemnaceae; Eriocaulaceae 265 



membranous, narrowly obovate to oblong, palmately 3- to year in the summer condition. Sliikoku, Kyushu (accord- 



5-nerved, 4-6 mm. long, 1.5-2.5 mm. wide, purplish beneath; ing to S. Miki). Formosa, China, Malaysia, and Australia. 



roots 3-5; winter buds absent; plants growing throughout the 



2. LEMNA L. Ao-uki-kusa Zoku 



Fronds small, flat, free-floating or submersed, 1- to 5-nerved; root 1, with a thin root-cap, without a vascular bundle; ovary 

 with 1-6 ordiotropous or anatropous ovules; fruit ovoid. ^About 8 species, in warm-temperate and tropical regions. 



lA. Fronds submersed, with a slender stipe at one end, ovate-oblong, sagittate or truncate at base 1. L. trisiilca 



1 B. Fronds floating, broadly obovate, not stiped 2. L. paucicostala 



1. Lemna trisulca L. Hinji-mo. Fronds submersed, rounded at tip, rounded or very obtuse at base, entire, green, 

 flat, green, 8-10 mm. long, 2-4 mm. wide, narrowly deltoid to 3-nerved, sessile; root single, with an acute root-cap; ovules 



ovate-oblong or broadly deltoid-lanceolate, rather obtuse to orthotropous, erect. Common in ponds and paddy fields; 



subacute, minutely serrulate on the upper margin, 3-nerved, Hokkaido, Honshu, Shikoku, Kyushu. Widely distributed in 



truncate or rather sagittate and short-stiped at base, with 1 tropical regions. 



or few daughter fronds; root single, sometimes wanting. Lemna minor L. Ko-uki-kusa is a cosmopolitan species 



Ponds, ditches, and sdll waters; Hokkaido, Honshu, Shikoku. allied to No. 2, differing in the obtuse root-cap, horizontal 

 Europe, Asia, Africa, Australia, and N. America. semianatropous ovules and fronds purplish beneath. Re- 



2. Lemna paucicostata Hegelm. Ao-uki-kusa. Fronds ported from Hokkaido, 

 floating, obliquely ovate-elliptic, 3-5 mm. long, 2-4 mm. wide, 



3. WOLFFIA Horkel Mijinko-uki-kusa Zoku 



Fronds minute, free-floating, globose to hemispherical or ovoid, rootless and nerveless, producing lateral gemmae from one 



edge of the frond; ovary with a single orthotropous ovule; fruit globose, smooth. A few species, in tropical and temperate 



regions. 



1. WoUfia arrhiza (L.) Wimmer. Lemna arrhlza L.; convex beneath, more or less margined, about 0.7 mm. long, 



L. globosa Roxb.; W. microscopica sensu Miki, an etiam producing lateral gemmae from one end of the frond, with- 



KuRz(?) Mijinko-uki-kusa, Ko-tsubu-uki-kusa, Kona- out roots and nerves. Honshu (vicinity of Tokyo). 



uKi-KusA. Fronds ovoid-hemispherical, nearly flat above, Cosmopolitan. 



Fam. 46. ERIOCAULACEAE Hoshi-kusa Ka Pipewort Family 

 (Contributed by Dr. Tetsuo Koyama.) 



Herbs or semishrubby plants; stems short or nearly wanting; leaves linear, cauline or radical; peduncles surrounded below 

 by a tubular bladeless sheath; inflorescence a terminal involucrate head; flowers unisexual; perianth segments arranged in 2 

 series, each consisting of 2 to 3 segments, the outer sepaloid, usually connate, the inner petaloid, always free or rarely minute to 

 wanting; stamens in 2 or a single series; ovary superior, (1-) 2- or 3-locular, the ovule single in each locule, orthotropous, 



pendulous, the style solitary, 2- or 3-fid; capsule loculicidally dehiscent; embryo short, at the apical end of mealy albumen. 



Eleven genera, with about 1,000 species, in botii hemispheres. 



1. ERIOCAULON L. Hoshi-kusa Zoku 



Herbs: stems usually very short; leaves radical, rosulate, linear; flowers dimerous or trimerous, monoecious, both .sexes in the 

 same head, subtended by a scalelike (floral) bract; staminate flowers: calyx of 2 to 3, free or connate sepals, the corolla tubular, 

 distinctiy or indistinctly 2- or 3-lobed at apex, the stamens in two series; pistillate flowers: sepals free or connate, the petals 



free, rarely none, bearing a small black gland at the apex. About 250 species, in wet places in the tropical and temperate 



regions of bodi hemispheres; all of our species flowering in autumn. 



I A. Flowers wholly dimerous \. H. deccmflorum 



IB. Flowers at least partially trimerous. 

 2A. Sepals of pistillate flowers 2-3, free. 



3A. Pistillate flowers without petals; sepals 2; anthers white to gray. 



4A. Bracts white, chartaceous, gradually narrowed above to a short awn; pistillate sepals winged on back. 



2. £. echiniitatiim var. seticuipe 



4B. Bracts hyaline, membranous, obtuse to subacute; pistillate sepals not winged on back 3. £. cineretim var. sicboldianum 



3B. Pistillate flowers petaliferous; sepals 2-3; anthers black. 



5A. Involucral bracts much longer than the disc flowers; calyx white 4. E. zyolanii 



5B. Involucral bracts shorter than the disc flowers; calyx bluish black. 



6A. Stem distinct, elongate; leaves narrow, 1 -nerved 5. E. caitlijerum 



6B. Stem almost wanting; leaves several- to many-nerved. 



