358 OaoER 53.— LOASACE^. 



N. Y. to Newfoundland. Rhizome prostrate, creeping, sending up several stems 

 or scapes which are simple and 4 to 12' high. Fls. small, purplish white, sessile, 

 alternate, a little shorter than the bracts, the upper ones j . Jl. 

 6 'M. ambiguum Nutt. Lvs. many, submersed ones pinnate, with capillary seg- 

 ments, middle ones pectinate, upper linear, petiolate, toothed or entire ; ils. mostly 

 S ; petals oblong, somewhat persistent ; stam. 4 ; carpels smooth, not ridged on 

 the back. — In ponds and ditches, Penn. to Mass. Sts. floating, upper end emerged, 

 with minute fls. and linear floral Iva. (M. natans DC.) In other situations it varies 

 as follows. 



/8. LIMOSDM Nutt. St. procumbent and rooting ; lvs. all linear, rigid, often en- 

 tire. — Muddy places, where it is a small, creeping and branching plant. (M. 

 procumbens Bw.) 

 y. CAPiLLAOEUM Torr. Lvs. all immersed and capillary. — Ponds. 



H. HIPPU'RIS, L. Mare's Tail (Gr. Irrvio^, a horse, ovpd, a tail.) 

 Calyx with a minute, entire limb crowning the ovary ; corolla none ; 

 stamen 1, inserted on the margin of the calyx ; anther 2-lobed, com- 

 pressed ; style 1, longer than the stamen, stigmatio the whole length in 

 a groove of the anther ; seed 1. — 'U- Aquatic herbs. St. simple. Lvs. 

 verticillate, entire. Fls. axillary, minute. 



H. vulgaris L. Lvs. in verticils of 8 to 12, linear, acute, smooth, entire ; fls. soli- 

 tary, often S S J . — In the borders of ponds and lakes, Penn. to Arc. Am., very- 

 rare. Rhizome with long, verticillate fibers. St. erect, jointed, 1 to 2f high. 

 The flowers are the simplest in structure of all that are called perfect, consisting 

 merely of I stamen, 1 pistil, 1 seed in a l-celled ovary, with neither calyx lobes 

 nor corolla. May, Jn. 



Order LIII. LOASACEtE. Loasads. 



Serbs often hispid with stinging hairs, with leaves opposite or alternate and no 

 stipules. Flowers axillary, soUtary. Calyx adherent to the ovary, 4 or 5-parted, 

 lobes persistent, equal. Petals 5 or 10, in 2 circles, often cucullate, inserted on the 

 calyx. Stmnens indefinite, uiserted with the petals, free or cohering in several sets: 

 Ovury l-celled, with several parietal placentae, or one central. Sttjle 1. Ocuks 

 pendulous. Embryo in the axis of fleshy albumen. 



Genera 18, species 70, natives of America. 



MENTZE^LIA, L. (In honor of C. Mentzel, physician to the Elector 

 of Brandenburg.) Calyx tubular, limb 5-parted ; petals 5 to 10, flat, 

 spreading; stamens oo, 30 to 200; ovary inferior; styles 3, filiform, 

 connate, and often spirally twisted ; stigmas simple, minute ; capsule 1- 

 celled, many-seeded. — Branching herbs. Lvs. alternate. 



1 M. oligospenna Nutt. Very rough, with barbed hairs ; st. diohotomous ; lvs. 

 ovaU-lanceolaie, tapering to very short petioles, lobed or incisely dentate ; petals en- 

 tire, cuspidate, expanding in sunshine ; stam. 20 or more, shorter than the petals ; 

 caps. 3 to 5-seeded. — % Dry or rocky places, Pike Co., Ill (Mead), and Mo. to Tex. 

 Rt. tuberous. St. If high, divaricately branched. Lvs. 10 to 15" by 6 to 8", 

 upper ones ovate. Fls. solitary, of a deep, goldeu yellow, 8 to 10" diam., very 

 fugacious. Caps, cylindrio, very small. May — Jl. 



2 M. Lindleyi Torr. & Gr. Golden Baetonia. Hispid ; lvs. ovate-lance- 

 olate, pinnatifid, lobes often dentate; fls. solitary or nearly so, terminal; petals 

 broadly obovate, very abruptly acuminate; filaments filiform, and with tlje seeds 

 mimerous.—Q) Gardens. St. decumbent, branching, 1 to 3f in length, with golden 

 yellow fla. 2 to 3' diam'., the beauty of which is greatly heightened by innumera- 

 ble, thread-like, yellow stamens. (Bartonia aurea Lindl.) f California. 



