73. CER.4.T0PHYLLACEJE. — 74. CALLITRICHACE-E. 293 
oblong-ovate attenuate acute, 1. linear-oblong sessile, upper 1. 
cordate at the base, inv.-glands lunate with bhuit horns, caps, 
smooth with a dorsal line. — E. B. 2255. — St. solitaiy, 2 — 3 feet 
high, purplish. L. many, in 4 rows. — Truly ■wald in a few stony 
and rocky woods, where it appears for 2 or 3 years after the 
bushes have been cut. Also naturalized on cidtivated ground. 
B. VI. VII. Caper Spurge. E. 
3. Mercttria'lis Linyi. Mercury. 
1. M. peren'nis (L.); st. simple, 1. stalked oblong-lanceolate 
rough, female fl. on long common staUcs, creeping. — E. B. 1872. — 
St. a foot high, usually naked below. Fl. in lax spikes. — ^. M. 
ovata (Steud.) ; 1. nearly sessile ovate. — Woods and thickets. 
yS. Hurstpiei'point, Suss. Mr. 3Iitte)i. P. IV. V. - E. S. I. 
2. M. an'nua (L.) ; st. branched, 1. stalked ovate or ovate-ob- 
long smooth, female fl. nearly sessile, root fibrous. — E. B. 559. 
St. 29. 16.— Height 6—12 m.' Bright green. Much branched. 
— (3. M. ambigua (L.) ; 1. lanceolate, fl. whorled male and female 
intennixed. E. B. S. 2816.— Waste and cultivated laud. /3. Jer- 
sey. Isle of Wight. Dr. Bromjield. A. VHI. IX. E. S. I. 
Order LXXIII. CEEATOPHYLLACE^. 
Fl. monoecious. Perianth fi-ee, in many divisions. Anth. 12 
— 20, sessile, 2-celled, 2-pointed ; cells again partially divided. — 
Perianth none. Ovary 1-celled. Seed 1, pendulous. Embryo 
sti-aight ; cotyledons 4, alternately smaller. — Only one genus. 
1. Ceratophtl'lttm Linn. Hornwort. 
1. C. demer'sttm (L.) ; segments of 1. linear-filiform, fr. wing- 
less ha-\ang a spine on each side near the base and tipped with 
the cm-ved subidate style. — E. B. 947. — L. 2 — 4 times forked, 
dark green ; segments of uppermost 1. broader and more rigid. 
—Ponds and ditches. P. VI. VII. E. S. I. 
2. C. mhrner'suin (L.) ; segments of 1. setaceous, fr. destitute 
of spines covered when ripe with cylindrical tubercles and tipped 
with the short curved style. — E. B. 679. — L. pale green. Young 
fr. smooth. — Ponds and ditches. P. VI. VII. E. 
Order LXXrV. CALLITRICHACE.E. 
Fl. mostly monoecious, solitaiy, minute, usually with 2 white 
bracts, no perianth. Stam. 1. Filament long. Anth. reniform, 
1-celled, opening transversely at the top. — Perianth none. Ovary 
