PLATE XXV.— COMMON CLUB-MOSS (Lycopodium clavatum) and Selaginella. 



(Qhiefly f)-om Luenuen't " Metlicinisch-Pharmaceutische Botanil:") 



Lycopodium. 



Club-mosses, as the common name denotes, are moss-like plants, having slender herbaceous stems, clothed with delicate small leaves, 

 and found in mountainous situations or stony, wet places. 



The fossil forms of the Carboniferous period, of which Lepidodendron is the most characteristic, instead of being herbaceous, were 

 large trees. 



The prostrate creeping Stem is very leafy, and much branched. From the under surface arise the roots, and from the upper surface 

 the upright fertile shoots, ending generally in two fertile spikes. 



The Leaves are hair-pointed, and arranged in a close spiral round the stem. 



The Modified Leaves bearing the sporangia are shorter and broader than the ordinary leaves, though. sometimes they are quite the 

 same. 



The numerous minute spores (Fig. 4) are applied to various uses. They contain a* quantity of resinous matter, and their wall is of 

 a greasy nature. This resinous quality renders them readily combustible, hence they are used as "vegetable sulphur" for producing an 

 artificial and sudden flame to represent lightning at theatres, and their greasy coat has caused them to be used for dusting over pills, 

 thus preventing the contained pill from touching the tongue. 



Pig. 1. Creeping Stem branches dichotomously, and also the Roots. 



Leaves thickly set round the stem. 



Spikes usually in pairs, mounted on a stalk. 

 Fig. 2. Leaf one-nerved and irregularly toothed, with a long hair-point variable in length. 



Pig. 3. Fertile leaf bearing Sporangium at its base on the upper surface. Sporangium kidney-shaped, splitting into two valves, 

 and producing only one kind of spore. 



Fig. 4. Spore with netted markings fading away towards apex. » 



Three converging ridges, along which exospore ruptures. 



Fig. 5. Prothallus of Lycopodium, discovered by Fankhauser in the autumn of 1872. 



It is an underground solid structure, without chlorophyll, pretty smooth on the under surface, but deeply 

 grooved on the upper. Antheridia and Archegonia are developed in the grooves. 



Life History Diagram. — The discovery of the Prothallus shows that the Lycopod, in its reproductive processes, is more nearly 

 allied to Ferns, such as Adder's Tongue (Ophioglossum), than to Selaginella, beside which its vegetative characters seemed to 

 place it 



The fertile leaves of the spike bear sporangia on their inner base, the spores of which are of one kind. The spore on 

 germination produces a prothallus, underground, solid, without chlorophyll, independent of the spore, and with Antheridia and 

 Archegonia. The embryo resulting from fertilization forms a foot embedded in the tissue of the prothallus, and grows up 

 into the young plant 



CLASSIFICATION OF LYCOPODIUM. 



Sub-kingdom. — Vascular Cryptogams. 

 Class. — Dichotomae. 



Stem and Roots branching dichotomously. 



Leaves small and simple. 



Sporangia solitary. 



Spores of one or two kinds. 

 Order. — Lycopodiaceae. 



Leaves without a ligule. 



Spores of one kind. 



Prothallus large and independent. 

 Genus. — Lycopodium, only British genus. 

 Species. — Clavatum. 



Spikes usually in pairs, long-stalked. 



Selaginella. 



Selaginella, with only one British species, the lesser Club-moss, has a special interest from the fact that it not only belongs to the 

 highest group of Cryptogams, but that it shows a gradual passage from the reproductive processes characteristic of Cryptogams to those 

 of Phanerogams. It is this phase of its character which will receive special attention now. 



The Reproductive Structures are of two kinds, and, generally speaking, the Macrosporangia are only produced on the lower leaves, 

 and Microsporangia on the upper. In Pilularia, Sporangia of two kinds were produced, springing in tufts from the inner (or upper) 

 surface of four modified leaves arranged in a whorl, but here they spring singly and separately from the upper surface of leaves arranged 

 spirally. In the one case the leaves were all at one level, united at their edges, and enclosing the Sporangia, here the leaves are drawn 

 out into a spiral, and bear the Sporangia without enclosing them. 



The developing Embryo (as in Fig. 14) will show the points of contact with higher plants. For the first time there appears in the 

 spore, along with the female prothallus, yet distinct from it, a mass of cells which supply nutriment to the young and growing embryo. 

 This is the Endosperm of higher plants. Further, the embryo as soon as it forms the rudiments of the stem bearing its two first leaves, 

 or Cotyledons, gives rise to a Suspensor, as in higher plants. 



Fig. 6. Specimens may readily be obtained from hothouses, where they are grown on damp spots for their beautiful and delicate 

 foliage. 



Leaves on creeping stem in two lateral rows and two dorsal rows. Those of the upper surface, or dorsal row, 

 are relatively smaller than those of the lateral row. 



Upright Fertile Spike, with similar leaves arranged spirally, and bearing sporangia in their axils. 



Fig. 7. Embed portion of fertile spike in paraffin and make longitudinal section. 



Fibro-vascular bundle in centre of axis, united with those going to leaves. 



Air-spaces surrounding fibro-vascular bundles, the interspaces composed of numerous green, branching cell- 

 filaments. 



Outer cells colourless. 



Leaf with membraneous Ligule at its base, and bearing a Macrosporangium in its axil. 

 Leaf on opposite side bearing Microsporangium in its axil. 

 Microsporangium containing numerous small spores — the Microspores. 



Macrosporangium, the largest, containing four Macrospores arranged like a tetrahedron, and several aborted 

 mother-cells of spores. 



