MEDICAL BOTANY - A.G. Serbin - 2003

SECTION 3. SYSTEMATICS

SUPERKINGDOM EUKARYOTA — EUCARYOTA. KINGDOM PLANTAE

SPORE PLANTS

DIVISION LYCOPHYTA — LYCOPHYTA (LYCOPODIOPHYTA)

Clubmosses are among the most ancient vascular microphyllous plants, which emerged during the Silurian period of the Paleozoic era. Today, there are approximately 1,000 species.

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The progressing generation is the sporophyte. These are perennial, usually evergreen, herbaceous plants. The underground organ is a rhizome (class Lycopodiopsida) or a rhizophore — an underground SHOOT with spirally arranged adventitious roots (class Isoetopsida). Shoot growth is apical and determinate, with dichotomous branching. Shoots lack well-defined nodes and internodes, and are densely covered with green microphylls. These are vegetative, spirally arranged leaves with 1 – 2 Veins. At the base on the inner side, they may bear an outgrowth called a ligule (class Isoetopsida). Spore-bearing leaves, or sporophylls, either resemble vegetative leaves or differ from them. They form spore-bearing zones on the stem or are gathered into terminal spore-bearing spikes, or strobili (class Lycopodiopsida). Single sporangia are located in the axils of the sporophylls. Spores typically have a trilete tetrad scar and are either uniform (Lycopodiopsida) or of two types (Isoetopsida).

The reduced generation is the gametophyte, or prothallium. The gametophytes of homosporous forms (class Lycopodiopsida) are bisexual, underground or semi-underground, fleshy, with or without rhizoids, and lead a saprophytic or semi-saprophytic lifestyle through Symbiosis with Fungi. They live from 5 to 15 years. The gametophytes of heterosporous forms (class Isoetopsida) are unisexual, non-green, develop inside spores utilizing their nutrient reserves, and live for several weeks. Spermatozoids are bi- or multiflagellate. The zygote lacks a resting stage.

The life cycles and The Structure of sporophytes and gametophytes of homosporous and heterosporous lycophytes are exemplified by Lycopodium clavatum and Selaginella selaginoides (see Fig. 3.101 and 3.103).

It should be remembered that certain clubmoss species contain paralyzing curare-like poisons! Some clubmosses are used in veterinary medicine and for dye production. In medicine, A number of species are employed in treating nicotine addiction, alcoholism, and eye diseases. The spores, rich in non-drying fatty oil, serve as dusting powder (lycopodium or natural talc) and are used for coating pills.

Class Lycopodiopsida

Family Lycopodiaceae

Stag's-horn clubmoss (running pine) — Lycopodium clavatum (Fig. 3.101). Found from the tropical zone to the tundra in coniferous and mixed forests, on heather moors, and along the shores of lakes and bogs. It forms patches and "witch's rings" — groups of plants that have spread via Vegetative Reproduction.

The sporophyte is an evergreen herbaceous plant up to 50 cm tall. The shoots branch unequally dichotomously, forming creeping stems with adventitious roots and fungal hyphae, as well as ascending, leafy shoots of limited growth. Leaves are spiral, linear-lanceolate, soft, flat, sickle-shaped and curved upward, nearly entire-margined, and tapering into a long, white Hair tip. Spore-bearing spikes are 2 – 4 cm long, cylindrical, located in pairs (rarely 3 – 5) on long stalks bearing sparse, thin leaves that closely adjoin the axis. Sporophylls are rounded-ovate with acute apices. Sporangia are single, axillary, and Kidney-shaped. Spores are small, tetrahedral, pale yellow, Water-repellent, and greasy and velvety to the Touch. Spore germination is subterranean and prolonged.

Fig. 3.101. Developmental cycle of Lycopodium clavatum: A — sporophyte; B — gametophyte; 1 — creeping shoot with adventitious roots; 2 — ascending shoots; 3 — stalk of the spore-bearing spikes; 4 — leaves of the ascending shoot (a) and the stalk of the spore-bearing spikes (b); 5 — spore-bearing spikes; 6 — sporophylls: ventral (c) and dorsal (d) views; 7 — sporangia; 8 — spores; 9 — germinating spore; 10 — archegonium; 11 — antheridium; 12 — Fertilization; 13 — fertilized egg Cell;

14 — development of a new sporophyte on the gametophyte

The gametophyte is a monoecious plantlet in the form of a colorless bulb 2 – 3 cm in diameter, bearing rhizoids and fungal mycelium. Antheridia and archegonia are located on the upper surface. Following fertilization, a sporophyte embryo develops from the zygote, which initially derives Nutrition from the gametophyte. Once roots appear, it shifts to an independent lifestyle and develops into a new individual (see Fig. 3.101).

The herb of Lycopodium clavatum contains Alkaloids and is used as an emollient, diuretic, antirheumatic, and adsorbent agent. Spores containing fatty oil are used as a dusting powder.

Fir clubmoss (stiff clubmoss) — Lycopodium selago (Huperzia selago) (Fig. 3.102). Grows in shady, damp coniferous forests, on rocks, and stony slopes. A perennial herbaceous plant 10 – 25 cm long. Shoots are ascending, densely leafy, and branch equally dichotomously almost from the base. Prostrate sections of the shoot bear adventitious roots and soil fungal hyphae that provide saprophytic nutrition. Brood buds for vegetative renewal form at the shoot apices. Leaves are rigid, glossy, linear-lanceolate, acute, entire-margined or finely toothed, and reflexed or angled obliquely upward. Spore-bearing spikes are absent; instead, single kidney-shaped sporangia are located at the base of ordinary leaves in the middle part of the shoot. Spores germinate within 3 – 8 years. The herb contains alkaloids, Glycosides, sugars, Enzymes, and Trace Elements. It is used to treat chronic alcoholism, hysteria, Pulmonary Tuberculosis, Metabolic Disorders, and vomiting. Used as a dye plant. The plant is poisonous! Protected by law!

Fig. 3.102. Lycopodium selago