ORDER 51. MYRTACE^E. 121 



1 P. palustrls L. Lvs. linear-lanceolate, sharply serrate above the water, those be 



low (if any) pinnatifid. li Swamps : common. 6 20'. Lvs. 1 2'. June, July. 



2 I", pectinacea Lam. Lvs. all pectinate, with linear-subulate segm. ; fr. obtusely 



3-angled. it Sandy swamps, Ms. (rare) to Fla. 5 1(K ; long creepers at base. Jl. Aug. 



2. MYRIOPHYLLUM, Vaill. WATER MILFOIL. Flowers 8 , or fre- 

 quently $ . Calyx 4-tootlied in the $ and ? flowers, 4-parted in the 3 . 

 P3t. 4, often inconspicuous or none. Sta. 4 8. Stig. 4. pubescent, sessile. 

 Fr. of 4 nut-like carpels, cohering by their inner angles, xnt Submersed 

 Ivs. parted into capillary segments. Upper fls. usually $ , middles ones 

 5 , lower ? , greenish, emerging in summer. 



Stamens 8. Carpels smooth and even. Leaves whorled in 3's, rarely in 4'e . . NOB. 1, 2 



Stamens 4. Carpels ridged on the back. Leaves whoiied in 4's and 5's Nos. 3, 4 



Carpels smooth and even. Leaves alternate or wanting Nos. 5, 6 



1 OT. spicatum L. Floral Ivs. ovate, entire, shorter than the flowers, the rest all pin- 



nately capillary ; fls. in term, spikes. Deep waters, fls. emerging. lOf. 



2 Jtt. verticillatum L. Floral Ivs. pectinate-pinnatifid, much longer than the flow 



ers, the lower pinnately-setaceous. Spikes leafy, terminal. Slow waters. 



3 M. heteroplif Hum MX. Floral Ivs. ovate-lanceolate, serrate, longer than the fls. 



crowded, the rest pinnately or pectinately capillary. Ponds : rare. 



4 PH. scabratum MX. Floral Ivs. linear, pectinately toothed ; fr. roughened, sharply 



angled ; verticils axillary. Shallow waters. 6 IS'. Capillary segments few. 



5 Jtt. tenellum Bw. Erect and almost leafless ; floral leaves or bracts alternate, mi- 



nute, entire, obtuse ; fls. s; petals linear. Water edges, N. Eng. N. Y. and N. Scapes 

 4 12', from long creeping rhizomes. Fls. purplish-white, sessile. 



6 HI. umbiguiim Nutt. Lvs. many, submersed ones pinnate, with capillary seg- 



ments, middle ones pectinate, upper linear ; fls. mostly & . Floating in ponds and 

 ditches. Ms. to Ga. 



/3. limosum. Small, procumbent, rooting, in muddy places ; Ivs. all linear. 



y. capillaceum. Very slender ; Ivs. all immersed and capillary, in ponds. 



3. HIPPURIS, L. MARE'S TAIL. Calyx with a minute, entire limb 

 crowning the ovary. Cor. 0. Sta. 1, inserted on the margin of the calyx. 

 Anth. 2-lobed, compressed. Style 1, longer than the stamen, stigmatic the 

 whole length. Seed 1. ? K St. simple. Lvs. verticillate, entire. Fls. ax- 

 illary, greenish. 



H. viilgarls L. Lvs. in verticils of 8 to 12, linear, acute, smooth, entire ; fls. solitary, 

 minute. Borders of ponds, marshes. N. and W. : rare. 1 2f. Dakotah (Matthews) 



ORDER LI. MYRTACE.E. MYRTLEBLOOMS. 



Trees and shrubs, without stipules. Leaves opposite, entire, punctate, 

 usually with a vein running close to the margin. Calyx adherent below to 

 the compound ovary, the limb 4- or 5-cleft, valvate. Petals as many as the 

 segments of the cnlyx. Stamens numerous. Anthers introrse. Style and 

 stigma simple. Fruit with many seeds. Albumen none. 



Our Myrtleblooms are either tender exotics, or indigenous far South, 

 The following table must suffice for their recognition. 



* Calyx truncate. .Petals connate into a caducous calyptra or lid. . .(a) 



a Fru.t a capsule. Slam. free. Australian trees, alternate-leaved EUCALYPTUS. 



a Fruit a berry. Stara. free. Leaves opposite. Small trees in S. Florida CALYPTRANTHES 



Cal. 4-lobed. Pet. 4, spreading. Fr. bac. Lvs. opp. Trees, shrubs. S. Fla. AUxpirf, Ac. .EUGKNiA. I 



Cal. 5-lobed. Pet. 5, spreading. Stam. loug-cxserted. Shrubs. Cultivated. . .(&) 



