EQUl] 



Cfje Crea^urg at 2Sntang. 



458 



gams, remarkable for the external resem- 

 blance which they bear in habit to Casua- 

 rinaov Ephedra, and as regards the heads 

 of fructification to Zamia. All resemblance, 

 however, ceases there, aikl the natural 

 affinities of the plants are with ferns. 

 The plants are often perennial, new shoots 

 being thrown up from the creeping rhi- 

 zomes. The spores germinate like those of 

 ferns, and produce a sort of prothallus, 

 which bears archegones and antherids. 

 The latter yield large spiral fringed sper- 

 matozoids like those of ferns. The shoots 

 are jointed, each articulation having a 

 toothed membranous sheath, and are often 

 repeatedly divided, with whorls of branches 

 and branchiets. The fructification is pro- 

 duced in the form of terminal cones, con- 

 sisting of a number of peltate scales, each 

 of which produces a circle of spore-cases, 

 perpendicular to the axis, and opening by 

 a longitudinal fissure, the walls of which 

 consist of very delicate spiral tissue. The 

 spores have a spiral coat, which ultimately 

 splits up into two bodies, each with two 

 clavateends, and attached by their centre 

 so as to look like four stamens. These, 

 however, are nothing more than the un- 

 rolled spiral of which the spore coats 

 consist. 



The structure of the rhizome and of the 

 lower part of the stem is very curious, and 

 quite different from anything in ferns. In 

 an early stage there is a central column of 

 cellular tissue in the rhizome, from which 

 eight plates radiate, being connected with 

 an external cylinder of the same nature, 

 and leaving between them distinct cavi- 

 ties. At a later period new tissue grows 

 from the walls of the plates, and ultimately 

 obliterates the cavities. Opposite to each 

 of the plates is a vascular bundle, consist- 

 ing of distinct annular vessels passing 

 into spirals. In ferns, on the contrary, the 

 vessels are mostly scalariform. In the fruit- 

 bearing stems the cavities are tnore abun- 

 dant with various modifications. 



Equiseta, or Horsetails, are found in most 

 parts of the world, though they are want- 

 ing in Australia and New Zealand. In the 

 temperate regions they are mostly inhabi- 

 tants of fields and wet places, and some- 

 times of loose sands, which they tend to 

 bind together by their delicate rootlets, and 

 have stiff erect stems capable of support- 

 ing themselves. But in warmer regions, 

 and even in Lisbon, as E. debile and elonga- 

 tum, they require the support of bushes 

 to which they cling. They sometimes 

 attain a considerable size, as E. giganteum, 

 though never reaching the dimensions of 

 undoubted fossil Equisetacece. An immense 

 quantity of silica, amounting sometimes to 

 half their weight when consumed, is taken 

 up into their substance : and, according to 

 the observations of Brewster, the par- 

 ticles, each of which has a double axis of 

 refraction, are disposed in rows parallel to 

 the axis, and occasionally forming ovals 

 connected together like the jewels of a 

 necklace. In consequence of this abund- i 

 ance of silica, like Tripoli, some of the j 

 species are used for polishing various ' 



articles, and large quantities of E. 7>?/< male 

 are imported into this country under the 

 name of polishing or Dutch rushes. Some 

 of the species have been used in medicine, 



Equisetum xylochsetum. 



but their virtues are doubtful. The 

 rhizomes contain a considerable quantity 

 of starch, and the starch cells sometimes 

 exhibit a kind of circulation. [M. J. B.] 



EQUITANT. "When the two sides of a 

 leaf are brought together and adhere ex- 

 cept at the base, where they enclose an op- 

 posite leaf whose sides are in the same 

 state : hence they look as if they rode on 

 each other. 



ERABLE. (Fr.) Acer. — DENORVEGE 

 Acer platanoides. — DURET. Acer opu- 

 Ufolium. — JASPB. Acer pensylvanieum. 

 — NEGUNDO. Negundo. — OBIER. Acer 

 opulifolium. 



ERAGROSTIS. A very extensive genus 

 of grasses, belonging to the tribe Festu- 

 cece, distinguished by having the inflor- 

 escence in more or less compound or decom- 

 pound panicles ; glumes four to ten-flower- 

 ed; pales imbricated in two ranks, the 

 upper reflexed with the edges turned 

 back ; stamens two or three ; styles two, 

 with feathery stigmas ; seeds loose, two- 

 horned, not furrowed. In Steudel's Synop- 

 sis there are 243 species described ; these 

 range more or less over the whole surface 

 of the globe, Asia being the quarter where 

 they mostly abound. Europe has only six 

 species, all of which are natives of the 

 southern portion only. The appellation is 

 derived from two Greek words, signifying 

 when combined Love-grass. Most of the 

 kinds are handsome, and some of them are 

 sufficiently hardy for being cultivated as 

 ornamental grasses in Britain. [D.M.] 



ERANTHEMUM. A considerable genus 

 of Acanthacece, containing nearly fifty 

 species, widely distributed over the tropi- 

 cal and subtropical regions of the Old and 

 K"ewWorlds,chiefly growing, at a greater or 

 less height, on mountains. They are shrubs 

 or under-shrubs, with entire or serrated 

 leaves, and showy often spicate flowers, 

 whose corolla is salver-shaped, with along 



