614 



HALORAGIDACEAE. 



VOL. II. 



3. MYRIOPHYLLUM [Yaill.] L. Sp. PI. 992. 1753. 



Aquatic herbs, with verticillate or alternate leaves, the emersed ones entire, dentate or 

 pectinate, the submerged ones pinnatifid into capillary segments, the axillary commonly 

 monoecious 2-bracted flowers often interruptedly spicate. Upper flowers generally staminate 

 with a very short calyx-tube, its limb 2-4-lobed, or none; petals 2-4; stamens 4-8 Intermedi- 

 ate flowers often perfect. Lower flowers pistillate, the calyx more or less deeply 4-grooved 

 and with 4 minute lobes, or none ; ovary 2-4-celled ; ovule I in each cavity, pendulous ; styles 

 4, short, often plumose. Fruit splitting at maturity into 4 bony i-seeded indehiscent carpels 

 which are smooth, angled or tuberculate on the back. [Greek, myriad-leaved.] 



About 20 species, of wide geographic distribution. In addition to the following, 2 others occur 

 in the western United States. The plants flower in summer. Type species : Myriophyllum spi- 

 catum L. 



Carpels smooth or minutely papillose. 

 Stamens 8 ; petals fugacious. 

 Floral bracts verticillate. 



Floral bracts entire or toothed, shorter than the flowers. 

 Floral bracts pectinate, shorter or longer than the flowers. 

 Floral bracts alternate. 

 Stamens 4 ; petals not fugacious. 



Stem scape-like, erect, nearly leafless. 

 Stem creeping or floating, leafy. 

 Carpels rough, tuberculate or ridged. 

 Flowers on emersed spikes. 



Floral leaves ovate or lanceolate, serrate. 

 Floral leaves linear, pectinate. 

 Flowers on submersed stems. 



1. M. spicatum. 



2. M. verticillatum. 



3. M. alterniflorum. 



4. M. tenellum. 



5. M.humile. 



6. M. heterophyllum. 



7. M. pinnatum. 



8. M. Farwellii. 



i. Myriophyllum spicatum L. Spiked Water- Mil foil. Fig. 3081. 



Myriophyllum spicatum L. Sp. PI. 992. 1753- 



Submerged leaves in whorls of 4's and 5's, dissected 

 into capillary divisions. Floral leaves (bracts) ovate, 

 entire or serrate, usually shorter than the flowers ; spike 

 i'-3' long; petals 4, deciduous; stamens 8; stigmas 

 short; fruit about i" long and \\" thick; carpels rounded 

 on the back, with a deep wide groove between them, 

 smooth, or very rarely slightly rugose. 



In deep water, Newfoundland to Manitoba, Alaska, Mary- 

 land, Michigan, Kansas, New Mexico and California. Also 

 in Europe and Asia. Both this species and the next have 

 been erroneously recorded from Florida. Meakin. Water- 

 navelwort. 



2. Myriophyllum verticillatum L. Whorled Water- Mil foil. Fig. 3082. 



Myriophyllum verticillatum L. Sp. PI. 992. 1753. 



Submerged leaves in crowded whorls of 3's and 4's, the 

 capillary divisions very slender, sometimes finer than those 

 of M. spicatum, about 10 pairs, i'-ii' long, often minutely 

 scabrate. Floral leaves pectinate or pectinate-pinnatifid, 

 longer or shorter than the flowers; spike 2'-6' long; petals 

 of the staminate flowers 4, purplish; stamens 8; fruit i"- 

 ij" long, and about i" thick, somewhat gibbous at the base. 



In both deep and shallow water, Quebec and Ontario to New 

 York, west to Minnesota and British Columbia. Also in Europe 

 and Asia. Myriad-leaf. 



