Plants of Calamites have been seen erect by Mr. Binney, and he has determined that what were called leaves or branches by some are in reality roots. Mr. Binney gives a full description of various Calamites, under the name of Calamodendron commune, in his Memoir published by the Palæontographical Society, 1868. There are between 50 and 60 species recorded.[13]
In Spitzbergen, in rocks of the Carboniferous epoch, there have been found Calamites, Sigillaria, Lepidodendron, and ferns, apparently the same as those found in the Carboniferous epoch in Europe—Calamites radiatus, Lepidodendron Veltheimianum, Sigillaria distans, Stigmaria ficoides. Some species—Sigillaria Malmgreni, Lepidodendron Carneggiannum, and L. Wilkianum—seem to be peculiar to Bear Island.
Fig. 47.
Fig. 47. Fruits of Equisetum and Calamites. 1. Equisetum arvense, L. 2. Portion of sporangium wall. 3, 4. Spores, with the elaters free. 5. Longitudinal section of the part of one side of cone. 6. Transverse section of cone. 7. Calamites (Volkmannia) Binneyi, Carr., magnified three times. 8. Portion of the sporangium wall. 9. Two spores. 10. Longitudinal section of the part of one side of cone. 11. Transverse section of cone.
According to Carruthers the Equisetaceæ are represented in Britain by the two genera Calamites found in primary beds, and Equisetum found in secondary rocks and living at the present day. The difference in the structure of their fruits is shown in woodcut 47. The fruit of Calamites, called Volkmannia Binneyi (woodcut 47, 7), is a small slender cone composed of alternating whorls of imbricate scales, twelve in each verticil. The scales completely conceal the leaves connected with the fructification. The fruit-bearing leaves are stalked, peltate, and are arranged in whorls of 6. There are four sporangia borne on the under-surface of the peltate leaves. These spore-cases have cellular parietes, and in their interior there is a deposit of cellulose in the form of short truncate processes not unlike imperfect spirals. The spores are spherical, and appear to have thread-like processes proceeding from them, similar to elaters. The fruit-cone bears a marked resemblance to the fruit of Equisetum in its fruit-bearing leaves, sporangia, spores, and elaters (see [Figs. 18, 19, 20, 21]). In the modern plant all the leaves of the cone are fructiferous, while in the fossil plant some are fruit-bearing, and others are like the ordinary leaves of the plant. It is thought that the fossil may be reckoned as having a somewhat higher position than that possessed by the living genus.
Fig. 48.
Fig. 48. Foliage and fruits of Calamites. 1 and 2. Asterophyllites; 3 and 4. Annularia; 5 and 6. Sphenophyllum.
The different forms of foliage called Asterophyllites, Sphenophyllum, and Annularia, belong to the one genus Calamites, but they may form, perhaps, well-characterised sections when their fruits are better known. In woodcut 48 representations are given of the foliage and fruit of varieties of Calamites. In 1 and 2 we see the simplest form called Asterophyllites. The leaves are linear and slender, with a single rib. The form called Annularia (3 and 4) differs chiefly in having a larger amount of cellular tissue spread out on either side of the midrib. This form has a different aspect in a fossil state from the other, from its whorls of numerous broad leaves spread out on the surface of deposition, while the acicular leaves of Asterophyllites have penetrated the soft mud, and are generally preserved in the position they originally occupied in reference to the supporting branch. The third form (5 and 6) is called Sphenophyllum, and consists of whorls of wedge-shaped leaves, with one or more bifurcating veins. They occur like those of Annularia, spread out on the surface of the shale.