66 POISONOUS PLANTS. 



URTICA DIOICA {British). 



COMMON NETTLE. 



Uritcacece. — Leaves cordate, with stinging hairs. — Flowers in 

 much-branched axillary clusters ; usually dioecious. — Waysides ; 

 abundant. 2-4ft. Perenn. July and Aug. Green. 



Toxic principle.— FO^mC ACID. 



URTICA URENS {British). 



SMALL NETTLE. 



Urticacecs. — Leaves elliptical, with stinging hairs. — Flowers 

 in loose racemes. — Waste ground. — Sin.-ift. Ann. June-Oct. ; 

 green. 



Toxic principle -FO^yilC ACID. 



URTICA PILULIFERA {British). 



ROMAN NETTLE. 



UrticacecB. — Leaves opposite, ovate, deeply serrated, with 

 stinging hairs. Fertile flowers in globular heads. Waste 

 ground. i-2ft. Ann. June and July. Green. 



Toxic principle. — FORMIC ACID, also contained in U. crenu- 

 lenta, U. urentissima, U. gigas. 



RHUS VENENATA. 

 RHUS VERNIX {N. America). 



POISON ELDER. — POISON ASH. — POISON SUMACH. — SVi^AMP 

 SUMACH. — DOG WOOD. 



AnacardiacecB. — A hardy, deciduous tree. 6-i8ft. — Flowers 

 green, small, polygamous, in loose and slender, axillary and 

 bractate terminal panicles. Calyx 4-6 parted, persistent ; 

 petals 4-6, much spreading, imbricated ; stamens 4-10. July. — 

 Fruit in small, dry, compressed drupes. — Leaves alt. ; simple ; 

 leaflets obovate- oblong, entire, rather glabrous than pubescent, 

 reticulately veined below, veins above red-purple, becoming red 

 on decay. — Stem contains a milky juice. 



Toxic principle.— 'PYViOGXlAjlC ACII>, also contained in 

 R. arborea, R. caustica, R. diversiloba, R. metopium, R. radicans. 



