Remarks on the so-called woody and vascular tissues of ferns / by George Ogilvie.
- Ogilvie, George
- Date:
- 1860
Licence: Public Domain Mark
Credit: Remarks on the so-called woody and vascular tissues of ferns / by George Ogilvie. Source: Wellcome Collection.
11/26 page 9
![terposed between them and the dark cortical portion of the stem, it is hardly possible to separate the vascular coat in the same wav from the delicate cellular tissue of the medulla which it in- * vests. (PI. V. fig. 3; compare with fig. 4.) The rhizomes of Hyrnenophyllum Tunhridgense and H. Wil- soni are of interest from ])resenting a transition to the type of stem characteristic of the Lycopodiacese, as there is but a single vascular bundle, lying in the axis of the bristle-like rhizome (PI. VI. fig. 5). This central fasciculus contains four or five scalariform vessels, surrounded by a cambium-layer. Round this, again, there is a thin stratum of pale parenchyma, and a cortical layer of brown tissue, fibrous and much indurated inter- nally, but loose and chaffy on the exterior. The transition-cha¬ racter of the stem is of the more interest that we have in it all the essentials of the rhizome of Osmunda. We have only to concch^e the stout caudex of the latter drawn out till it is reduced to the thread-like dimensions of the rhizome of Hymenophylluniy to have a complete transformation of the one into the other; for when the vascular cord of Osmunda is reduced to the dimen¬ sions of that of Hyrnenophyllum, its cellular pith necessarily disappears, as a single series of vessels of the ordinary thickness must come to occupy its whole diameter. In all the stems noticed above, with the dark tissue much developed, and particularly in Osmunda regalis, Blechnum boreale, Fteris nquiiina, and Allosorus crispus, there is a very remarkable contrast between the hardness of the coloured tracts and the great softness and delicacy of the pale parenchyma and of the vascular bundles (especially in their cambium-la3^er). The close juxtaposition of tissues of such different powers of resistance adds much to the difficulty of obtaining thin sections for micro- sco])ical purposes. The permanency of these tissues is in pro¬ portion to their hardness. Thus in the rhizomes of the com¬ mon Rraken, after long exposure the cortical layer and the two internal bands of dark substance are sometimes the only parts left, the pale parenchyma and the vascular bundles having all disappeared by the process of natural decay. And when this dark substance forms the main element, as in Osmunda and Blechnum, the whole rootstock has a like protracted duration, as has been already observed of the former species. In connexion with this subject, the question suggests itself, wliether the hard brown tissue now referred to (ovphceenchyma, as it might be called) corresponds to the pro})er wood of the higher or phanerogamic plants ? There is some difficulty in answering this question, arising principally out of the ambiguity of the term “ woody tissue.I do not see any reason to doubt that in many of the higher plants there are hard parts, commonly called](https://iiif.wellcomecollection.org/image/b30564451_0011.jp2/full/800%2C/0/default.jpg)
