The Calamarieae, now known to have been the chief Palaeozoic representatives of the Horsetail stock, attained the dimensions of trees, reaching, according to Grand' Eury, a height of from 30 to 60 metres, and showed in all respects a higher and more varied organization than their recent successors.
Different genera have been founded on leaf-bearing branches of Calamarieae; apart from Archaeocalamites, already mentioned, and Autophyllites (Grand' Eury), in both of which the leaves were dichotomous, we have Annularia, Asterophyllites and Calamocladus (in Grand' Eury's limited sense), with simple leaves.
In Asterophyllites., the generic distinction of which from Annularia is not always clear, the narrow linear leaves are in crowded whorls, and the ultimate branches distichously arranged; in the Calamocladus of Grand' Eury - characteristic of the Upper Coal Measures - the whorls are more remote, and the twigs polystichous in arrangement.
According to Grand' Eury, the Palaeostachya fructification was most commonly associated with Asterophyllites foliage.
Various other seeds of the same type are known, and in a great number of instances Grand' Eury has found the fronds of Neuropterideae (Medulloseae) in close association with definite species of seeds, so there can be little doubt that the whole family was seed-bearing.
In 1905 Grand' Eury discovered the seeds of Pecopteris Pluckeneti, an Upper Coal Measure species, attached, in immense numbers, to the fronds, which are but little modified as compared with the ordinary vegetative foliage.
In those stems which have been referred with certainty to the Cordaiteae there is no centripetal wood; the spiral elements are adjacent to the pith, as in a recent Conifer or Cycad; certain stems, however, are known which connect this type of structure with that of the Lyginodendreae; this, for example, is the case in the Permian genus Poroxylon, investigated by Bertrand and Renault, which in general structure has much in common with Cordaiteae, but possesses strands of primary wood, mainly centripetal, at the (After Grand' Eury, modified.
Our knowledge of the Cordaiteae (the typical family of the class Cordaitales) is chiefly due to the French investigators, Grand' Eury and Renault, who successfully brought into connexion the various fragmentary remains, and made known their exact structure.
There is good evidence that many of the seeds belonged to Cordaitales, especially those seeds which had a flattened form, such as Cardiocarpus, Cycadinocarpus, Samaropsis, &c. Seeds of this kind have been found in connexion with the Cordaianthus inflorescences; the winged seeds'of Samaropsis, borne on long pedicels, are attributed by Grand' Eury to the genus Dorycordaites.
- Eury pterus Fischeri, Eichwald.