1702 CXLVII. ALISMACE^. 



Ordek CXLVII. ALISMACEiB. 



Flowers hermaphrodite or unisexual, regular. Perianth when perfect of 

 6 segments, imbricate in 2 series, the 8 outer ones membranous or herbaceous, 

 the 3 inner larger and petal-like, often very fugacious. Stamens 6, 9 or 

 indefinite, hypogynous or slightly connected with the base of the segments, but 

 when isomerous with them not usually opposite their centres ; filaments filiform 

 or flattened ; anthers erect, with 2 parallel cells opening laterally in longitudinal 

 slits. Ovary of 3, 6 or many carpels, quite distinct or shortly connate, each 

 tapering into a short style or with a sessile terminal stigma; ovules 1, 2 or few, 

 erect from the base of the cavity, or the funicle of the inner one shortly adnate 

 to the inner angle, or numerous and parietal. In fruit the carpels ripen into 

 indehiscent nutlets, or when several-seeded are variously dehiscent. Seeds erect 

 or when geveral ascending or spreading, with a thin testa and inner membrane ; 

 no albumen. Embryo either straight and of the shape of the seed, or more 

 frequently horse-shoe shaped ; radicle inferior. — Marsh or water plants. Leaves 

 radical on long petioles. Flowering stems leafless, or rarely, in species not 

 Australian, leafy. Flowers in terminal umbels,- racemes and panicles. 



The Order is lepiesented in the marshes, ponds, and shallow waters of most parts of the 

 globe. 



Tribe I. AliameSB. — Fruit of 3 or more achenes. 



Perianth perfect. Flowers pedicellate, paniculate, umbellate or almost 



racemose. 



Carpels 1-seeded, indehiscent, scarcely beaked 1. Alisma. 



Carpels 2-seeded, tapering into divaricate beaks falling off by a transverse 



rupture near the base 2. Dasiasonium. 



Tbibe II. Butomete. — Fruit of follicles. 



Carpels many-seeded, dehiscent along the inner suture 3. Butomopsis. 



1. ALISMA, Linn. 



(Derived from the Celtic word for water.) 



Flowers usually hermaphrodite. Perianth of 6 segments, 3 outer ones 

 membranous or almost herbaceous, 8 inner large and petal-like. Stamens 6. 

 Ovules solitary in each carpel. Fruit-carpels indehiscent, either about 6 or 

 numerous, arranged in a ring round the depressed axis, or (in species not 

 Australian separated by some into a distinct genus) irregularly crowded in a 

 globular head. Seed ovate or oblong with a horse-shoe embryo. — Aquatic herbs, 

 erect or in species not Australian floating, with radical leaves on long petioles. 

 Flowers either in a terminal umbel with or without whorls of pedicellate flowers 

 below it, or in a panicle with whorled branches, each bearing a similar umbel. 



The genus is widely spread over the temperate and warm regions of the globe. 

 Carpels 6 or fewer, rarely 7 or 8. 

 Leaves deeply cordate with a narrow sinus, the outer primary veins on 

 each side confluent in the auricles, transverse veinlets not very 

 close and more or less connected by reticulations. 



Carpels about 3 lines long, hard, often muricate 1, A. acantltocarpum. 



Carpels under 2 lines long, smooth or tuberculate, the pericarp not 



very hard. ■••••;•■■■. 2. A. oligococciim. 



Leaves broadly cordate or reniforra, the primary vems all distinct, 

 transverse veinlets very numerous and closely parallel. Carpels 

 somewhat drupaceous 3. ^. reniforme 



1. A. acanthocarpum (fruit spiny), F. v. M. Fragm. i. 23, viii. 214; 

 Benth. Fl. Austr. vii. 185. Leaves broadly ovate or orbicular, deeply cordate 

 with a narrow sinus and angular auricles, glandular-dotted, with 11 to 17 

 primary nerves, the outer ones on each side confluent within the margin of the 

 auricles, the transverse veinlets not very close and often connected by reticula- 

 tions. Panicle usually 6 to 9in. long and broad, the branches and pedicels 3 or 



