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preserve the veinless acerose state of Coniferse, but expand and form veins, 
which are then forked and of uniform thickness, just as in Ferns. 
Geography. Natives of the temperate climates of all the quarters of the 
globe ; they occasionally make their appearance in hot latitudes, as in the In- 
dian Archipelago, but they can hardly be called common anywhere. 
Properties. Resinous like Coniferse, and often valuable for their timber. 
The Dacrydium taxifolium, or Kakaterro of New Zealand acquires a height of 
200 feet. Ph. Journ. 13. 378. Its branches may be manufactured into 
spruce beer. The succulent covering of the Yew fruit is fcetid,and is said to be 
deleterious by De Candolle ; there is also a prejudice against the seeds. The 
seeds of Salisburia and Podocarpus neriifolia are large and eatable. 
GENERA. 
Taxus, L. Phyllocladus, Rich. Salisburia, Sm. 
Podocarpus, L’Herit. Thalamia, Spreng. Ginkgo, Thunb. 
Dacrydium, Banks. Brownetera, Rich. 
Order CCXXXII. EQUISETACE^. The Horse-tail Tribe. 
EQuiSETACEiE, DC. FI. Ft. 2. 580. (1805); Agardh Aph. 119. (1822) ; Kaulfuss Enum. 
Filicum, 1. (1824) ; Greville Flora Edin. xiii. (1824) ; Adolphe Brongniart Hist, 
Veg. Foss. 99. (1828.) 
Essential Character. — Inflorescence cone-like, consisting of peltate scales. Flowers 
naked, collected in great numbers in the inside of the deflected lobes of the peltate scales, 
which lobes open inwards by a longitudinal slit. Stamens 4, clavate, wrapped round a 
naked ovule, and remarkably hygrometrical. — Leafless branched plants with a striated 
fistular stem, in the cuticle of which silex is secreted ; the articulations separable and 
surrounded by a membranous toothed sheath. Stem flstular, with many longitudinal 
cavities in its circumference ; chiefly consisting of cellular substance, but coated externally 
with a layer of hard woody tubes from which plates of a similar nature project towards the 
centre, partially dividing the longitudinal cavities from each other. Stomates arranged 
longitudinally on the cuticle. Spiral vessels very few. 
Affinities. The very remarkable plants known by the vulgar name of 
horsetails, seem to have no very decided affinity to any existing order. With 
Ferns their relation is not at all obvious, depending almost entirely upon the sup- 
posed want of sexes. In the arrangement and appearance of their reproduc- 
tive organs they have a striking resemblance to Zamia, and in general aspect 
to Casuarina. Their germination is that of Cellular plants, and approaches 
nearly to Mosses. Upon the whole, they must be considered an exceedingly 
anomalous tribe, approaching Coniferse through Cycadaceie more closely than 
any thing else. The curious structure of their stem is well described by Ad. 
Brongniart in his History of Fossil Vegetables, as are, indeed, all the parts of 
their organisation : see Tables 11 and 12 of that work. This ingenious wri- 
ter entertains the opinion that the green body, which is known to be the spo- 
rule, is a naked ovule, and the 4 swollen filaments that surround it 4 grains of 
pollen united in pairs to the base of the ovule. It is probable that the nearest 
approach to the structure of sexual organs does take place here, and that, con- 
sidering the analogy between the thecae of Equisetum and the lobes of the 
anther of Coniferse, and between the filaments of the former and the quater- 
nary grains of pollen of Cycas, the parallel drawn by Brongniart is substantially 
just, but it must, at the same time, I think, be admitted, that it is very 
doubtful whether, in this order, the parts are any thing more than represen- 
tatives of the sexual apparatus, without the power of performing its functions. 
