7. Myosurus L. Mousetail 



Very small acaulescent annual herbs, with fibrous roots; leaves in a radical tuft, 

 linear to filiform or at first spatulate, entire; scapes simple, one-flowered, the 

 yellowish or whitish flower succeeded by the slender spike or (in depauperate 

 specimens) oblong head of carpels; sepals 5, spurred at the base; petals 5, small 

 and narrow, raised on a slender claw at the summit of which is a nectariferous pit; 

 stamens 5 to 20; achenes numerous, somewhat 3- or 4-sided, apiculate, crowded 

 on a very long and slender spikelike receptacle, the seed suspended. 



About 15 species of local occurrence but widely distributed. 



1. Achenes when mature roundish, with a dorsal cup or border nearly surround- 

 ing the base of the beak, the cup often larger than the body of 

 the achene 1. M. cupulatus. 



1. Achene when mature more or less quadrangular, without cup or border, keeled 



dorsally from base to apex, the subulate beak not strongly flattened 

 laterally (2) 



2(1). Back of the achene scarcely wider on each side than the very prominent 

 keel, the latter prolonged into a beak at least half as long as the 

 body of the achene 2. M. aristatus. 



2. Back of the achene distinctly wider on each side than the relative low keel, 



the latter prolonged into a beak much less than half as long as the 

 body of the achene, or the beak sometimes obsolete. .3. M. minimus. 



1. Myosurus cupulatus Wats. Fig. 452. 



Tufted annual, often very diminutive, 3-8 cm. tall; leaves linear to linear- 

 spatulate, 1-5 cm. long; sepals 5 or 6, oblong, the variable spur often short or 

 "blunt-tapered" and sometimes as much as one third as long as the blade; petals 

 linear-filiform, with a narrow, elongate claw 4 to 5 times as long as the narrow 

 short-oblong blade; scapes 3-8 cm. long; fruiting spike slender, 2-5 cm. long; 

 achenes with a thickened margin producing a cuplike depression on the back from 

 which protrudes the divergent beak; seed short-oblong, flattened. 



Vernally wet spots, seepage areas and in shelter of boulders, in N. M. (Grant 

 and Sierra cos.) and Ariz. (Greenlee to Mohave, s. to Cochise, Santa Cruz and 

 Pima COS.), Feb.-July; N. M. to Calif, and Son. 



This species may readily be distinguished by the loose-fitting achenes which 

 at maturity are separated by obvious spaces. 



2. Myosurus aristatus Benth. ex Hook. Fig. 453. 



Tufted annual; leaves linear to linear-spatulate, 1-5 cm. long, with a broad 

 almost membranous base; scapes very slender, 2-5 cm. tall; sepals oblong, erect 

 or spreading, with a slender spur from one half as long to fully as long as the 

 blade; petals present or (at maturity) often none; fruiting spike 5-10 mm. long; 

 achenes somewhat quadrate in outline, the back sharply keeled and extending to 

 the elongate divergent sometimes falcate beak. 



In wet and muddy places in N. M. (Bernalillo and San Juan cos.) and Ariz. 

 (Coconino and Pima cos.), Mar.-June; Neb. to B. C, s. to N.M., Ariz, and Calif.; 

 S.A. 



As Mason (1957) noted, M. aristatus may be readily distinguished by the 

 elongate, divergent beaks of the achene, which are fully as long as the body of 

 the achene, and by the very short spike, which, because of the achene, appears 

 somewhat bristly. 



3. Myosurus minimus L. Fig. 454. 



Leaves narrowly linear to filiform, blunt, 3-15 cm. long; scape 3-15 cm. long; 

 sepals oblong, 2-3 mm. long; spurs slender, acute, 1-3 mm. long; petals linear to 



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