428 CALLITRICHACE^. (WATER-STARWORTS.) 



senting the most reduced form of the Halorageaa, p. 174. The so-called 

 perfect flower is considered to be a staminate and a pistillate, or two stam- 

 inate and one pistillate naked flowers in the same axil, each of a single 

 stamen or pistil.) 

 The elaboration of our species is contributed by Dr. G. Engelmann. 



1. CALLITRICHE, L. Water-Stakwoet. 



riowers monoecious, solitary or 2 or 3 together in the axil of the same leaf, 

 wholly naked or between a pair of membranaceous bracts. Sterile flower a sin- 

 gle stamen : filament bearing a heart-shaped 4-celled anther, which by confluence 

 becomes one-celled, and opens by a single slit. Fertile flower a single 4-celled 

 ovary, either sessile or pedicelled, bearing 2 distinct and filiform sessile, usually 

 persistent stigmas. Ovule soUtary in each cell. Fruit nut-like, compressed, 4- 

 lobed, 4-celled, separating at maturity into as many closed 1-seeded portions. 

 Seed anatropous, suspended, filling the cell : embryo slender, straight or slightly 

 curved, in the axis and nearly the length of the oily allnimen. — Sinooth, or beset 

 with minute stellate scales (visible only under the microscope), with spatulateor 

 linear leaves, both forms often occurring on the same stem. (Name from koKos, 

 beautiful, and 6pi^, hair, from the almost capillary and usually tufted stems of 

 the commoner species.) 



§ I. Terrestrial species. Small annuals, forming tufts on merely moist soil; 

 destitute of stellate scales and of bracts : leaves uniform, very small, obovate or 

 wedge-shaped, Z-nerved, crowded, provided with stomata : filament not lengthen- 

 ing : carpels connate. 



1. C. Austini, Engelm. Fruit small, broader than high, deeply notched 

 above and below, on a pedicel often nearly of its own length ; lobes of the fruit 

 narrowly winged and with a deep groove between them, wings denticulate ; per- 

 sistent stigmas shorter than the fruit, spreading or reflcxed ; leaves obovate. — 

 On damp soil in open woods, fields and roads, New York and New Jersey ( C. F. 

 Austin) to Illinois, Missouri, Texas, Mexico, and South America. April -June. 

 — Half an inch or an inch high : leaves 1" - 2" long : fruit J" in diameter. 



C. PEPLOiDES, Nutt. and C. NuttAllii, Torr. (C. pedunculosa, Null.), — 

 the former with subsessile curiously gibbous fruit, the latter with long-peduncled 

 fruit with eversed keels, — are southwestern species of this section. 



§2. Amphibious species. Perennials? with elongated stems {occasionally quite 

 terrestrial as in the former, or wholly submersed as in the next section ) : leaves 

 with stellate scales and stomata, the floating ones obovate and 3-nerved, the sub- 

 mersed linear: flowers usually between a pair of bracts, rarely naked : pollen shed 

 only in the air ; the filament elongating aflei'wards : carpels in fruit connate. 



2. C. verna, L. Fruit (J" long) higher than broad, obovate, slightly ob- 

 cordate, usually thicker at the base than upwards, sessile, its lobes sharply keeled 

 or very nan'uwly winged upwards, and with a wide groove between them ; stig- 

 mas shorter than the fruit, almost erect, usually deciduous ; floating leaves 

 crowded in u, tuft, obovate, narrowed into a petiole. — Common in stagnant 

 waters, from Pennsylvania and New Jersey north and northwestward. April - 



