52 TlMEHRI. 
branches. It was first .gathered in this country by 
SCHOMBURGK. It grows on banks, in the fissures of 
rocks, and between the roots of trees. At the Botanic 
Gardens, where it has never been cultivated, it comes up 
frequently in the plant pots. 
General distribution. — America, from Cuba to South 
Brasil ; tropical Africa, Asia, and Polynesia. 
Order IX. Eauisetaeese. 
Rootstock creeping. Stems ereft, cylindrical, longitudinally furrowed, 
jointed at intervals, hollow except at the joints, which terminate in a 
completely circular monophyllous dentate margined sheath. Branches 
simple, springing through the lower part of the sheaths, whorled and 
spreading. No distinct leaves. Fructification terminal, on simple 
stems, in cone-shaped heads, which are composed of several horizontal 
tiers of peltate stipitate scales that bear on their underside 6-9 pale mem- 
branous micro-sporangia that open longitudinally in a'slit on the inner 
side. Spores minute, green, united to elastic wool-like threads (elaters) 
that are spontaneously irritant while dry. 
A single genus represents this order, numbering about 
thirty species, the principal part of which are spread 
through the north temperate zone, where they are in 
several European countries common and well known 
marsh plants, which in Britain go by the name of horse- 
tails and paddock-pipes. They form no leaves proper, but 
these organs are represented by the membranous sheaths 
of the joints. The branches are produced after the 
stems have developed, and they grow through the base 
of the sheaths. There is but one known Guiana species. 
Genus I. Ectuisotum. Linn. 
For characters refer to the order. 
/. Equisetum bogotense, H.B.K. — E. pratense, Hook. E. flagelliferum, 
Kunze. E. chilense, Presl. E. quitense, Fee. — Rootstock free-creeping, 
throwing up at intervals tufts of slender, virgate, stiffish shoots, which 
are 6.12 or 15 in. 1. hardly ali. thick; ribs 4-6 or 7. Teeth of the sheaths 
