550 BUXACEAE (BOX FAMILY) 



1. CALLfTRICHE L. WATER STARWORT 



The only genus. (Name from <taX6s, beautiful, and 6pi, hair, from the 

 slender stems.) 



* Small annuals, forming tufts on moist soil, destitute of stellate scales ; leaves 



uniform, very small, obovate or oblanceolate, 3-neroed, croicded; bracts 

 none. 



1. C. deflxa A. Br., var. Austin! (Engelm.) Hegelm. Stems 1-2.5 cm. high ; 

 fruit 0.7 mm. wide, broader than high, deeply notched above and below, on a 

 pedicel often nearly of its own length or almost sessile ; lobes of the fruit nar- 

 rowly winged and with a deep groove between them ; persistent stigmas shorter 

 than the fruit, spreading or reflexed ; leaves 2-4 mm. long. (C. Austini Engelm.) 

 Damp soil, Ct. to Del.; also from Tenn. to Mo. and Tex. (Mex., S. A.) 



* * Amphibious perennials ; leaves tcith stellate scales, the floating ones obovate 



and 3-nerved, the submersed linear (all uniform and narrowly oblong in 

 terrestrial forms) ; flowers usually between a pair of bracts. 



2. C. palustris L. Fruit 1 mm. long, higher than broad, obovate. slightly 

 obcordate, usually thickest at the base, sessile, its lobes sharply keeled or very 

 narrowly winged above, and with a wide groove between them ; stigmas shorter 

 than the fruit, almost erect, usually deciduous ; floating leaves crowded in a 

 tuft, obovate, narrowed into a petiole. (C. verna L., in part.) Common in 

 quiet waters. (Eu. ) 



3. C. heterophylla Pursh. Fruit smaller, as broad as or broader than high, 

 deeply emarginate. thick, almost ventricose, sessile or nearly so, its lobes obtusely 

 angled, with a small groove between them ; stigmas as long as the fruit, erect, 

 persistent ; floating leaves crowded in a tuft, broadly spatulate, often retuse, 

 abruptly narrowed into a long petiole. Quiet water, Nfd. to Md., La., and 

 westw. 



* * * Submersed perennial, with numerous uniform linear l-nerved leaves; floio- 



ers without bracts ; carpels separate nearly to the axis. 



4. C. autumnalis L. Stems 7-15 cm. high ; fruit large (2 mm. wide or 

 more), flattened, circular, deeply and narrowly notched, sessile or nearly so, its 

 lobes broadly winged, and with a very deep and narrow groove between them ; 

 stigmas very long, reflexed, deciduous ; leaves all linear from a broader base, 

 retuse or notched at the tip, 4-12 mm. long. (C. bifida Morong.) Lakes and 

 cold streams, w. Mass., L. Champlain, and w. Que. to L. Superior, and westw. 

 (Eu.) 



BUXACEAE (Box FAMILY) 



Perennial herbs or more often trees or shrubs, with simple opposite or alter- 

 nate usually evergreen leaves, watery juice and small greenish monoecious or 

 dioecious apetalous flowers; sepals imbricated or none; stamens opposite the 

 sepals or indefinite; carpels 3; ovary 3-celled ; styles 3, simple ; ovules (in ours) 

 geminate in the cells, suspended, the rhaphe dorsal. A small family, often 

 united with the Euphorbiaceae. 



1. PACHYSANDRA Michx 



Flowers monoecious, in naked spikes. Calyx 4-5-parted. Petals none. 

 Ster. Fl. Stamens 4, separate ; filaments long-exserted, thick and flat ; anthers 

 oblong-linear. Fert. Fl. Styles thick, awl-shaped, recurved, stigmatic down 

 their whole length inside. Capsule deeply 3-horned, 3-celled, splitting into 3 at 

 length 2-valved 2-seeded carpels. Nearly glabrous low and procumbent peren- 

 nial herbs, with matted creeping rootstocks, and alternate ovate or obovate 

 coarsely toothed leaves narrowed at base into a petiole. Flowers each 1-3- 

 bracted, the upper staminate, a few fertile ones at base, unpleasantly scented ; 



