68 DR. J. D. HOOKER ON THE GENERA AND SPECIES 



between the wood-wedges, where they appear as medullary rays, lastly passing into the 

 loose hexagonal tissue of the circumference of the rhizome. 



Seven narrow, elliptical, pale white wedges succeed the woody axis that occupies 

 the position of the pith, then radiate, are equal in length to about half the radius of the 

 rhizome, and placed midway between the periphery and circumference ; they are separated 

 li'om one another by the broad medullary rays, which assume the character of cubical, 

 hard, brittle wood-cells consolidated into one dense fii'm mass, protecting the softer tissue 

 between them. The wedges themselves are formed of delicate, white, large tubes, placed 

 end to end, and transversely marked with short lines, annular or spu-al bands. 



A broadly semilunar or kidney-shaped mass of wood-cells (liber) is placed externally 

 to each vascular Avedge and curves round its outer extremity, and is either placed closely 

 in apposition to the vascular wedge, or is separated fi'om it by a little cellular tissue. 

 These wood-cells are very large and thick- walled, are vertically elongated, and form long 

 parallelograms placed end to end, and adhering firmly one with another, become of a 

 dense yellow, almost crustaceous or osseous consistence ; their walls are everywhere per- 

 forated by minute canals, giving them a punctate appearance. 



The cortical jiortion or cellular tissue of the periphery is formed of hexagonal thick- 

 Avalled, almost woody cells, with perforated faces, and there are scattered irregularly 

 tlu'ough it very large sclerogen-cells and liber-bundles. This cortical portion is spongy 

 in consistence, and its hexagonal cells gradually pass into the cubical ones of the me- 

 dullary rays. 



Such appears to be the arrangement ia the first year ; in the second, more woody liber- 

 bundles are formed outside the semilunar ones, and alternating with them. The wedges 

 of vascular tissue do not appear to be added-to much, bxit there is an appearance of incom- 

 pleteness towards their circumference, as if a cambium-layer existed there. Strictly 

 speaking there are only two well-defined kinds of tissue in the rhizome :— 1. the delicate 

 vascular wedges, and 2. the coarse, hard, hexagonal cellular tissue of the periphery, which 

 becomes indurated between the vascular wedges and passes into the slender woody tubes 

 of the pith : the other tissues that are so conspicuous on a transverse section are not so 

 on a vertical one, the broad sclerogen-tubes of the semilunar bundles of liber differing 

 little from the cubical cells surrounding them, and the liber-bundles of the periphery 

 altogether resembling the long woody tubes of the j)ith. 



Many deviations may be found in different specimens from the above-described 

 arrangements of the cellular and vascular systems of the rhizome ; but all, I think, may 

 be easily reduced to this tyj)e. 



The vascular system of the peduncle consists of scattered bundles that run free and 

 imbranched from the rluzome to the capitulum, where they partially anastomose, forming 

 a plexus within the circumference, from which bundles are given off with great regularity 

 towards the base of each scale. I do not find the tissues of these bundles to be more 

 than rudimentary ; but traces of their each consisting of a bundle of woody tubes towards 

 the axis, followed by delicate transversely barred vessels, and these again by sclerogen"- 

 tubes, may, I think, be detected. 



Richard describes the styles as occasionally united at their bases, which I have never 

 seen ; he also states that he has never observed the plants to be truly parasitical, though 



