4. CRUCIFER.E. 129 



vince, because, as yet, Derbyshire is the only counU^ from 

 which I find the name of this species recorded, and the 

 Derbyshire plant is alpina or officinalis, not anglica. 



73. Armoracia rusticana, " Fl. Wetty 



Area (1 2 3 4 5 6 7 8 * 10 11 * 13 14 * * * 18). 



Alien. The difficulty of eradicating the horse-radish af- 

 ter it has once become estabhshed, is familiar to most gar- 

 deners. No wonder, therefore, that it should acquire and 

 keep such hold of the groimd in places where it is little 

 disturbed, as really to appear veiy like a genuine native. 

 Perhaps we might now look upon it as a denizen. 



74. SUBULARIA AQUATICA, Linn, ^t P"^. ///," d.OS/ 



Area * * * * [5] ^, 7 * .;^ * ^ * ^* * 15 16 17. 



South limit ui Anglesea and Caernarvonshire. 



North limit in Sutherland and Ross-sliire. 



Estimate of provinces U. Estimate of coimties-i^"! /i <:* /S" 



Latitude 53 — 59. Highland type of distribution. 



A. A. regions. Midagrarian — Midai'ctic zones. 



Descends to a shght altitude, in North Wales. 



Ascends to 700 yards, in East Highlands. 



Range of mean annual temperatm-e 47 — 39. 



Native. Lacustral. A scarce species, though it may 

 seem more so than is fact, on accoimt of the nature of its 

 habitat and the diminutive size of the plant. The Severn 

 pronnce is mentioned on the authority of Mr. Aiken, who 

 has pei-petrated so many blunders in reference to the Bo- 

 tany of Wales, as to render eveiy'thing doubtflU which 

 stands on the faith of his accuracy. 



s 



