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Updated: June 27, 2025
The SIGILLARIA, or "seal tree," was similar to the Lepidodendron, but its fluted trunk divided into even fewer branches, and was dotted with vertical rows of leaf scars, like the impressions of a seal. Both Lepidodendron and Sigillaria were anchored by means of great cablelike underground stems, which ran to long distances through the marshy ground.
Sir Charles Lyell mentions that in a colliery near Newcastle, no less than thirty sigillaria trees were standing in their natural position in an area of fifty yards square, the interior in each case being sandstone, which was surrounded by a bark of friable coal. The last great danger to which we have here to make reference, is the explosive action of a quantity of coal-dust in a dry condition.
"A single trunk of sigillaria in an erect forest presents an epitome of a coal-seam. Its roots represent the stigmaria underclay; its bark the compact coal; its woody axis, the mineral charcoal; its fallen leaves and fruits, with remains of herbaceous plants growing in its shade, mixed with a little earthy matter, the layers of coarse coal.
Another well-known form of carboniferous vegetation is that known as the Sigillaria, and, connected with this form is one, which was long familiar under the name of Stigmaria, but which has since been satisfactorily proved to have formed the branching root of the sigillaria.
Amongst the most remarkable are the sigillaria, of which large stems are very abundant, shewing that the interior has been soft, and the exterior fluted with separate leaves inserted in vertical rows along the flutings and the stigmaria, plants apparently calculated to flourish in marshes or pools, having a short, thick, fleshy stem, with a dome-shaped top, from which sprung branches of from twenty to thirty feet long.
None of these appearances could have been produced by subaqueous action. Though the roots of the Sigillaria bear more resemblance to the rhizomes of certain aquatic plants; yet, structurally, they are absolutely identical with the roots of Cycads, which the stems also resemble.
That very forest to which we went on that first day, and where we ate our luncheon from the trunk of a great petrified Sigillaria, had been discovered by Mr. Muir and his daughter a few years before as they were riding over the sandy plateau.
In a second specimen of an erect stump of a hollow tree 15 inches in diameter, the ribbed bark of which showed that it was a Sigillaria, and which belonged to the same forest as the specimen examined by us in 1852, Dr. Under the microscope, the head, with the eyes, mandible, and labrum, are well seen.
Binney found the specimen growing to the bottom of the trunk of one of the fossil trees with spotted stems, called Sigillaria; and so proved that this curious pitted stone is a piece of fossil root, or rather underground stem, like that which we found in the primrose, and that the little pits or dents in it are scars where the rootlets once were given off.
Sir Charles Lyell mentions an individual sigillaria 72 feet in length found at Newcastle, and a specimen taken from the Jarrow coal mine was more than 40 feet in length and 13 feet in diameter near the base. It is not often these trees are found erect, because the action of water, combined with natural decay, has generally thrown them down.
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