. Our native ferns and how to study them; with synoptical descriptions of the North American species. Ferns. 28 Our Native Ferns. CHAPTER FRUCTIFICATION IN FERNS. " But on St. John's mysterious night, Sacred to many a wizard spell, The hour when first to human sight Confest, the mystic fern^seed ; 30. Spores and Sporangia. —In the flowering plants (Pha- nerogamia) there is a true sex- ual reproduction, the ovules in the female organs (pistils) being fertilized by the pollen pro- Kig. 1. IDnlarged section through a sorus , , of Polypodium faXcatum, Kellogg, showing duced by
. Our native ferns and how to study them; with synoptical descriptions of the North American species. Ferns. 28 Our Native Ferns. CHAPTER FRUCTIFICATION IN FERNS. " But on St. John's mysterious night, Sacred to many a wizard spell, The hour when first to human sight Confest, the mystic fern^seed ; 30. Spores and Sporangia. —In the flowering plants (Pha- nerogamia) there is a true sex- ual reproduction, the ovules in the female organs (pistils) being fertilized by the pollen pro- Kig. 1. IDnlarged section through a sorus , , of Polypodium faXcatum, Kellogg, showing duced by the Stamens, thus grv- the stalked sporangia. (Original.)' ing rise to the embryo of the new plant. The Cryptogam ia on the contrary produce no flowers. Instead of seeds developed from fertilized ovuJes,minute spores are produced asexually from which new ferns are developed by a pecu- liar process of germination very unlike that of flowering plants. These spores are collected in little sacs known as sporangia or capsules. The sporangia in the true ferns (Polypodiace^) are collected in little clusters on the back of the frond or are variously arranged in lines along the veins or around the margins. (Fig. i). These clusters of sporangia are called sori, and may be naked, as in Polypodium, or provided with a special covering known as the indusium or in- volucre, as in Aspidium (Fig. 10). The various forms of the sori and indusia serve as the basis for classification into genera and tribes, while each sub-order has its peculiar form of sporangia. 31. In the PoLYPODiACE^ the sporangia are more or less completely surrounded with a joint- ed vertical ring and at maturity burst open trans-' versely and discharge their copious spores (Fig. 2). The clusters of sporangia may be marginal. Sporangium intramarginal or dorsal, according as they have of Poll/podium md- fj^gj^ position at the margin or more or less re- fr'pots.''''M'rifen^mote from it. They may be roundish, oblong or
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