XXXV.— THE TWAY-BLADE. 
Ltstera ovata Brown. 
O NE of the commonest species in the Family, yet one of the most striking in 
appearance, the Tway-blade is less like the rest of our terrestrial Orchids than 
any other type, and in the mechanism of its pollination is termed by Darwin “one of 
the most remarkable in the whole Order.” It is common in rich meadows, orchards, 
and copses, and these stations, together with the structure of the root, suggest that 
the plant prefers a certain amount of humus or leaf-mould in its soil. 
There are no tubercles ; but the premorse, ascending rhizome, or base of the 
stem, gives off long, slender, cylindrical, unbranched root-fibres, several together, 
throughout a considerable length. From this, ensheathed by one or two brown 
membranous leaf-sheaths, the stout, tapering, downy stem rises from one to two feet 
in height, its erect growth rendering an otherwise inconspicuous plant conspicuous. 
At a point generally nearer the base than the apex of this stem spring the two 
leaves, which form so much the most striking feature of the plant as to have given 
rise to all its popular names and its older scientific designation. In “Tway-blade” 
and “ Dufoil ” we have apparently the Old English and the Norman-French 
equivalents of the Bifolium which we find in Dodoens and Lobel, and which is 
merely translated as “ Herbe Bifoile ” in Parkinson. The herbalist last named 
speaks of it as 
“having onely two broad and short ribbed pale greene or hoary leaves, very like unto Plantane leaves but whiter set at 
the middle of the stalke one on each side, and compassing it at the bottome, sometimes it will get three leaves, which 
thereupon some reckoned to be a different sort, which is as we call it, but lusus nature by the abundance of nourishment in 
the plant, as it hapneth to very many other plants, (as to the Herba Paris as I said before, sometimes having five leaves, and 
sometimes sixe or seven, and sometimes wanting a leafe, when as ordinarily it hath but foure).” 
The leaves are only sub-opposite, the sheathing base of one being below that 
of the other, and we have found three-leaved specimens either with three leaves with 
equal divergence of 120 0 or with the extra leaf below one of the normal two. The 
colour of the foliage varies according to the light to which it is exposed and differs 
but little from that of surrounding grasses. It has, however, generally a yellowish 
tinge. The leaves are broadly ovate, acute, downy, with none of the lustre so general 
among Monocotyledons, and with three, five, or more prominent longitudinal veins. 
These do not branch and anastomose in the Dicotyledonous manner ; but are 
undoubtedly otherwise superficially like those of Plantago. They are from three to 
eight inches long. 
In May, the inflorescence rises between the two leaves, forming a raceme of 
numerous, loosely-arranged green flowers, each shortly pedicellate and arising in the 
axil of a minute ovate-acute bract. Both pedicel and ovary are twisted so as to 
produce the same inversion of the flower as in most other Orchids. The sepals and 
petals spread outwards, the former a deep green, the latter a yellower shade, whilst 
the labellum is bent sharply downwards in a vertical direction and is divided into 
