. A handbook of cryptogamic botany. Cryptogams. 94 VASCULAR CRYPTOGAMS fine anastomosing branches between the lateral veins. The placenta or' receptacle on which each sorus is seated is a cushion-like outgrowth of the vein. The sporanges are altogether destitute of an annulus; the wall always consists of several lajrers of cells. In Angiopteris the sporanges which make up a sorus are quite distinct, ovoid, and sessile, and dehisce by a vertical fissure on the, inner side. In all the other genera they are more or less confluent, and the entire boat-shaped sorus is then known as a synange ; but
. A handbook of cryptogamic botany. Cryptogams. 94 VASCULAR CRYPTOGAMS fine anastomosing branches between the lateral veins. The placenta or' receptacle on which each sorus is seated is a cushion-like outgrowth of the vein. The sporanges are altogether destitute of an annulus; the wall always consists of several lajrers of cells. In Angiopteris the sporanges which make up a sorus are quite distinct, ovoid, and sessile, and dehisce by a vertical fissure on the, inner side. In all the other genera they are more or less confluent, and the entire boat-shaped sorus is then known as a synange ; but each sporange still dehisces separately by a vertical slit on its inner side ; or, in, Danaea, by an apical pore. The coalescence is most complete in Kaulfussia, where the circular sorus has the appearance of a plurilocular basin. The sorus is usually surrounded by flat lobed hairs of epidermal origin, forming a kind of. Fig. 71.—A^ under side o^\ea£o{ An^o^ieris caudata ; B^ o{Maraitia ; s. son ; C, sorus of Marattia cut through, showing open sporanges. (After Goebel.) involucre. The true indusium is sometimes altogether wanting. The sporanges originate from the tissue of the leaf itself The placenta is first formed as a cushion-like outgrowth of the fertile vein, partly from the epiderm, partly from the subjacent tissue. On this originate, in Angiopteris, the separate sporanges as papillae, each composed of a number of cells. In Marattia, however, while the two rows of sporanges are distinct, those of each row are confluent from the first, but each has its own archespore. The primary mother-cells of the spores are formed at an early period within the archespore. The spores are formed in fours within their parent-cells, and resemble in general character those of typical ferns. Two different forms of spore sometimes occur in the same species, but they present no difference on. Please note that these images are extracted from scanned page images that may have been digitally e
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