Lycopodium rufescens Hook. An Andian species with stout dichotomously branched erect stems bears on the younger shoots crowded leaves with their thick and broadly triangular laminae pointing upwards, but on the older and thick shoots the laminae are strongly reflexed ([fig. 121], A). The lower part of the specimen represented in [fig. 121], A, shows tangentially elongated scars and persistent leaf-bases or cushions left on the stem after the removal of the free portions of the leathery leaves, a surface-feature which also characterises the Palaeozoic genus Lepidodendron. The reflexed leaves and persistent leaf-cushions are clearly seen in the piece of old stem of Lycopodium dichotomum Jacq., a tropical American species reproduced in [fig. 121], B. Such species as L. erythraeum Spring, and others with stiff lanceolate leaves exhibit a striking resemblance to the more slender shoots of some recent conifers, more especially Araucaria excelsa, A. Balansae, Cryptomeria, Dacrydium and other genera.
Fig. 121. Lycopodium.
- Lycopodium rufescens.
- L. dichotomum.
- L. tetragonum.
- L. nummularifolium.
- L. Dalhousianum.
- L. casuarinoides.
- L. volubile.
Fig. 122. Lycopodium squarrosum. The branches of the larger shoot terminate in cones. (From a plant in the Cambridge Botanic Garden. Reduced.)
In Lycopodium tetragonum Hook., ([fig. 121], C), a species from the Alpine region of the Andes, the long, pendulous and repeatedly forked branches bear four rows of fleshy ovate leaves and simulate the vegetative characters of certain conifers.
Fig. 123. Lycopodium cernuum.
(From a specimen in the Cambridge Herbarium. ½ nat. size.)
L. squarrosum Forst. ([fig. 122]) a tropical species from India, Polynesia, and other regions, is characterised by its stout stems reaching a diameter of 2·5 cm., bearing long pendulous branches with large terminal cones composed of sporophylls differing but slightly from the foliage leaves. The plant represented in the photograph serves as a good illustration of the practical identity in habit between Palaeozoic and recent genera.