GENUS 2. 



ARROW-GRASS FAMILY. 



93 



2. SCHEUCHZERIA L. Sp. PI. 338. 1753. 



Rush-like bog perennials with creeping rootstocks, and erect leafy stems, the leaves elon- 

 gated, half-rounded below and flat above, striate, furnished with a pore at the apex and a 

 membranous ligulate sheath at the base. Flowers small, racemose. Perianth 6-parted, regu- 

 larly 2-serial. persistent. Stamens 6, inserted at the base of the perianth-segments ; filaments 

 elongated ; anthers linear, basifixed, extrorse. Ovaries 3 or rarely 4-6, distinct or connate at 

 the base, i-celled, each cell with i or 2 collateral ovules. Stigmas sessile, papillose or slightly 

 fimbriate. Carpels divergent, inflated, coriaceous, i-2-seeded, follicle-like, laterally dehiscent. 

 Seeds straight or slightly curved, without endosperm. [Name in honor of Johann Jacob 

 Scheuchzer, 1672-1733, Swiss scientist.] 



A monotypic genus of the north temperate zone. 



i. Scheuchzeria palustris L. Fig. 220. 



Scheuchzeria palustris L. Sp. PI. 338. 1753- 



Leaves 4'-i6' long, the uppermost reduced to 

 bracts; stems solitary or several, usually clothed at 

 the base with the remains of old leaves, 4'-io' tall ; 

 sheaths of the basal leaves often 4' long with a 

 ligule long; pedicels 3"-io" long, spreading in 

 fruit ; flowers white, few, in a lax raceme ; perianth- 

 segments membranous, i-nerved, li" long, the inner 

 ones the narrower ; follicles 2"~4" long, slightly if 

 at all united at the base ; seeds oval, brown, 2*"-3" 

 long with a very hard coat. 



In bogs, Labrador to Hudson Bay and British Co- 

 lumbia, south to New Jersey, Pennsylvania, Wisconsin 

 and California. Also in Europe and Asia. Summer. 



Family 7. ALISMACEAE DC. Fl. Franc. 3: 181. 1805.^ 



WATER-PLANTAIN FAMILY. 



Aquatic or marsh herbs, mostly glabrous, with fibrous roots, scapose stems 

 and basal long-petioled sheathing leaves. Inflorescence racemose or paniculate. 

 Flowers regular, perfect, monoecious or dioecious, pedicelled, the pedicels verticil- 

 late and subtended by bracts. Receptacle flat or convex. Sepals 3, persistent. 

 Petals 3, larger, deciduous, imbricated in the bud. Stamens 6 or more ; anthers 

 2-celled, extrorse or dehiscing by lateral slits. Ovaries numerous or rarely few, 

 i-celled, usually with a single ovule in each cell. Carpels becoming achenes in 

 fruit in our species. Seeds uncinate-curved. Embryo horseshoe-shaped. Endo- 

 sperm none. Latex-tubes are found in all the species, according to Micheli. 



About 13 genera and 65 species, of wide distribution in fresh water swamps and streams. 

 Carpels borne in one series: achenes verticillate. i. Alisma. 



Carpels borne in several series ; achenes capitate. 

 Flowers perfect. 



Style not apical ; fruit-heads not echinate ; achene turgid, obscurely beaked. 2. Helianthium. 

 Style apical ; fruit-heads echinate : achene flat, prominently beaked. 3. Echinodonts. 



Flowers polygamous, monoecious or dioecious. 



Lower flowers of the inflorescence perfect. 4. Lophotocarpiis, 



Lower flowers of the inflorescence pistillate. 5. Sagittaria. 



i. ALISMA L. Sp. PI. 342. 1753. 



Perennial or rarely annual herbs with erect or floating leaves, the blades several-ribbed, 

 the ribs connected by transverse veinlets, or seemingly pinnately veined. Scapes short or 

 elongated. Inflorescence paniculate or umbellate-paniculate. Flowers small, numerous on 

 unequal 3-bracteolate pedicels, the petals white or rose-tinted. Stamens 6 or 9, subperigynous. 

 Ovaries few or many, borne in one whorl on a small flat receptacle, ripening into flattened 

 achenes which are 2-3-ribbed on the curved back and i-2-ribbed on the sides. [Greek, said 

 to be in reference to the occurrence of the typical species in saline situations.! 



About 10 species, widely distributed in temperate and tropical regions. Only the following 

 are known to occur in North America. Type species : Alisma Plantago-aqnatica L. 

 Achenes longer than wide, grooved on the back, the inner edges not meeting in the whorl ; 



peduncles and pedicels straight, ascending. 



Petals slightly longer than the sepals; corolla i I /2"-2 I 4" wide. i. A. snbcordatitm. 



Petals much longer than the sepals; corolla s"-6}/2" wide. 2. A. brevipes. 



Achenes as wide as long, ridged on the back, the inner edges meeting in the whorl ; peduncles and 

 pedicels recurved in fruit. 3. A. Geyeri. 



* Text revised by DR. JOHN KUNKEL SMALL. 



