54 HALORAGIDACEAE 



perennial with ovate to obovate, obtuse, coarsely dentate leaves, and purple 

 flowers in a dense cyme. A rare garden escape observed in Muscatine and 

 Johnson counties. 



HAMAMELIDACEAE Lindl. Witch Hazel Family. 



Small trees, with alternate simple petioled pinnately-veined leaves, 

 deciduous stipules, and axillary clustered or capitate flowers. Calyx 

 superior, imbricated in the bud, deciduous Petals inserted on the calyx, 

 valvate in the bud, deciduous. Ovary 2-celled. Styles 2, distinct. Repre- 

 sented with us by the genus Hamamelis L. 



r|. virginiana L. Witch-hazel. Tree 10-20 feet high; leaves oval or obovate, 

 wavy-toothed; flowers yellow; calyx 4-parted, with 3 scale-like leaves im- 

 mediately below; petals 4, long-linear; stamens 8, 4 fertile and alternate with 

 the petals, the remainder sterile; fruit a 2-celled woody capsule, opening at 

 the top, cells 1-seeded; seeds pendulous. Wooded ravines; flowers appearing 

 in October and the fruit the following July; infrequent; Clayton, Dubuque, 

 and Delaware counties. 



HALORAGIDACEAE A7. & Garcke. Water-millfoil Family. 



Marsh or aquatic plants. Leaves alternate, opposite or whorled, 

 entire or toothed; submerged leaves pinnately divided into narrow 

 segments. Flowers solitary, fascicled or whorled. sessile. Calyx su- 

 perior; tube coherent with the ovary. Petals small, inserted on the 

 calyx, alternate with its segments. Calyx and corolla sometimes want- 

 ing. Stamens 1-8, inserted with the petals. Ovary inferior, with 2-4 

 1-ovuled cells. 



Myriophyixum. Leaves whorled ; flowers monoecious or polygamous, the parts in fours. 

 Proserpinaca. Leaves alternate ; flowers perfect, the parts in threes. 

 Calwtrica. Leaves opposite ; flowers monoecious; sepals and petals wanting. 



MYRIOPhiYLLUM L. Water Mhylfoil. Perennial aquatics. Leaves 

 crowded or whorled, the submerged dissected into capillary divisions. Flow- 

 ers monoecious or polygamous in the axils of the upper leaves; the upper stam- 

 inate. Stamens 4-8. Fruit nut-like, 4-lobed, 4-celled. 



M. scabratum Mx. Stem slender; leaves in whorls of 4 or 5, lower pin- 

 nately parted, floral linear, toothed or serrate: stamens 4. Shallow lakes; 

 July: frequent; Muscatine, Appanoose, Ringgold, and Fremont counties. 

 (Af. pinnatum (Walt.) B. S. P.) 



M. heterophyllum Mx. Stem stout; leaves in 4\s and 5's; floral leaves 

 ovate or lanceolate, crowded, serrate, stamens 4. Lakes; July; Winnebago, 

 Cerro Gordo, and O'Brien counties. 



M. spicatum L. Leaves mostly pinnately-parted, capillary: floral leaves 

 small, shorter than the flowers, ovate, entire or toothed; flowers in an inter- 

 rupted spike; petals deciduous; stamens 8. Ponds; July; Muscatine. Cerro 

 Gordo, Story, and Dickinson counties. 



PF^OSERPIN ACA L. Perennial aquatics, with alternate lanceolate leaves, 

 and perfect small sessile axillary flowers. Calyx 3-sided, adnate to the ovary, 

 limb 3-parted. Petals wanting. Stamens 3-4. Stigmas 3, cylindrical. Fruit 

 bony. 3-4-angled, 3-4-celled, 3-4-seeded. 



P, palustris L. Mermaid weed, Glabrous, mostly simple; emersed leaves 

 oblong or linear-lanceolate, sharply serrate; the immersed leaves pectinate or 

 pectinate-piunatifid. the segments linear, stiff, acute, often serrulate, flowers 





