440 



plants amounts sometimes to thirteen per cent., and 

 the ashes of the plants have been found to contain 

 half their weight of that mineral. 



Eqidsetum hyemale, (rough horse-tail), contains so 

 much silex or flint, that its vegetable matter has been 

 removed, and yet its form has been retained. It is 

 used for the polishing of hard woods, brass, ivory, &c., 

 and may be made to act as a file. In Northumber- 

 land, the dairy-maids use it to scour and clean their 

 milk-pails. The plant is imported largely from Hol- 

 land under the name of Dutch rushes. 



On subjecting a portion of the cuticle of this plant 

 to the analysis of polarised light under a high mag- 

 nifying power, Sir David Brewster detected a beautiful 

 arrangement of the siliceous particles, which are dis- 

 tributed in two lines parallel to the axis of the steins, 

 and extending over the whole surface. In general 

 the particles form straight lines, but sometimes they 

 are grouped in oval forms, and connected togethe'r 

 like the beads of a necklace. Many of the particles 

 do not exceed the five-hundredth part of an inch in 

 diameter. From the observations which he made, 

 Sir David Brewster concludes, that the crystalline 

 portions of silex arc not foreign substances of acci- 

 dental occurrence, but are integral parts of the plant 

 itself, and probably perform some important function 

 in the processes of vegetable life. 



The fronds of Eqidsetum arvcnse are said to be 

 hurtful to such animals as feed on them in autumn. 

 Eqidsetum fluviat'de was eaten by the common people 

 among the Romans. It is said to be eaten by rein- 

 deer, and is used in some countries as food for cattle. 



The seeds of the Equisetums possess hygrometri- 

 cal properties : when exposed first to a dry and then 

 to a moist atmosphere, they move about in various 

 directions, according to the lengthening or shorten- 

 ing of the thread-like processes which are attached 

 to them. 



ERANTHEMUM (R. Brown). A genus of 

 ornamental under-shrubs, chiefly tropical. Liunsean 

 class and order Diandria Monogynia, and natural 

 order Acanthaccce, Generic character : calyx of four 

 equal parts ; corolla salver-shaped, limb five-cleft, 

 nearly equal ; stamens four, two of which are abortive, 

 two fertile ones protruding. This is a free flowering 

 genus in our stoves, thrives in a light rich soil, and 

 is easily increased by cuttings. 



ERANTHUS (Salisbury). This is the Helleborus 

 hyemalis of Linnaeus, and remarkable as being one of 

 the first flowering plants of the early spring, preced- 

 ing both the snowdrop and crocus. It is a polyan- 

 drious plant, and belongs to the natural order Ranun- 

 culacece. It is the winter aconite of English authors. 



EREMURUS (Bieberstein). A genus included 

 in the natural order Asphodeleae, and called Asphodelus 

 Altalcus by Pallas. It is a herbaceous perennial, in- 

 digenous to Siberia, and has a place in our flower 

 borders. 



ERIA (Lindley). An orchideous genus, thought 

 to be a Dendrobium by Dr. Hooker, but made a sepa- 

 rate genus by Dr. Lindley. It receives its name from 

 the extreme woolliness of the flower. Grown in turfy 

 moor earth, and propagated by dividing the root. 



ER1ANTHUS (Michaux). A genus of gigantic 

 grass, native of North America. It was supposed to 

 be a species of Saccharum by Persoon, but Michaux's 

 name is adopted. 



ERICA (Linnaeus). Heath. One of the most nu- 

 merous families occurring in the vegetable kingdom. 



;ERANTHEMUM ERICE^E. 



Five hundred and forty-three species are named in 

 published lists, besides numerous varieties. See 

 ERICE/E. ^ 



ERICEjE, or ERICINE.E. The Heath Tribe. 

 A natural order of monopetalous dicotyledonous 

 plants, containing nearly thirty genera, and upwards 

 of nine hundred known species. The order is allied 

 to Vacc'iuke and Campanulaccce, from both of which it 

 differs in its superior ovary. It also boars an affinity 

 to Epacridea: and Pyroluccce, but is distinguished from 

 the former by the structure of its anthers, and from 

 the latter by its general habit, and the structure of its 

 seeds. 



Its essential botanical characters are, calyx per- 

 sistent, inferior, four or five cleft ; corolla hypogjnous, 

 four or five cleft, withering ; stamens definite, equal 

 in number to the segments of the corolla, or twice as 

 many, inserted at the base of the calyx of the corolla ; 

 anthers two-celled, the cells hard and dry, separated 

 either at the apex or base, where they are furnished 

 with an appendix, and usually opening by pores ; 

 ovary free, surrounded at the base by a disk or by 

 scales ; one straight style, and a single undivided 

 or toothed stigma ; fruit capsular, many celled, with 

 central placentas ; seeds indefinite, minute. 



The plants belonging to this order are shrubs, or 

 under-shrubs, with evergreen, rigid, entire leaves with- 

 out stipules. They cover immense tracts of country 

 at the Cape of Good Hope, where upwards of three 

 hundred separate species are found. The common 

 heaths, or heather, form a considerable portion of the 

 vegetation of large districts in England and Scotland. 

 Heaths abound also in many parts of Europe, as well 

 as in North and South America, both within and 

 without the tropics. They are not common in 

 Northern Asia or India, and in Australia they are 

 scarcely known, their place being supplied by plants 

 belonging to the order Epacridece. 



In general the heaths possess bitter, astringent, 

 and diuretic properties. The chief genera of the 

 order are Erica, Calunta, Andromeda, Lcduni, Rhodo- 

 dendron, Azalea, Arbutus, Menziesia, Kalmia, and 

 Gaidthcria. 



Of the genus Erica, or true heath, there are five 

 species indigenous in Britain : Erica tetralix, cross- 

 leaved heath; Erica cinerca, five-leaved heath ; Erica 

 Mediterranca, vagans, and ciliaris. 



The two first species, along with common ling, 

 abound in all our moors, and are the badges of 

 the clans of Mac Donald and Mac Alister. From 

 the five-leaved heath the Picts used to make a deli- 

 cious and wholesome liquor. In the following lines 

 the poet alludes to this ancient practice, when he 

 addresses this heath a?, 



Sweet, modest flower, in lonely deserts dun, 

 Retiring still for converse with the sun, 

 Whose sweets invite the soaring lark to stoop, 

 And from thy cells the honeyed dew-bells scoop ! 

 Though unobtrusive all thy beauties shine, 

 Yet boast, thou rival of the purpling vino ! 

 For once thy mantling juice was seen to laugh 

 In pearly cups, which monarchs loved to quaff; 

 And frequent wake the wild inspired lay, 

 On Teviot's hills, beneath the Pictish sway. 



At the end of the last century, this tribe of plants 

 consisted of three or four British shrubs, and a single 

 Spanish one, but when the Cape of Good Hope fell 

 into the hands of the British, an amazing number of 

 species were immediately discovered. At the pre- 

 sent day, the species, and the varieties produced by 



