THE OLDER SPOROPHYTE 193 



seated origin of the roots of the Marattiaceae has often been figured and described. 

 The roots from the base of this plant showed the hexarch structure, the six xylem 

 masses being united in the middle of the stele. About half-way between the stele 

 and the epidermis of the root is a circle of large mucilage ducts, but these were quite 

 absent from the outer cortex. No mycorrhiza could be found, except that in the 

 outermost layers of cells, which constitute a rudimentary periderm, occasional fungus 

 filaments can be detected, but these are very different in appearance from the 

 typical mycorrhiza found in the primary root of the germ plant. No root hairs could 

 be found, but occasionally short stumps were seen which looked as if a root hair 

 had been broken off. 



f^'S- ^75> -^> shows three consecutive free-hand sections of a stem from a 

 plant of about the same size as the one we have just described, but evidently much 

 older, as there were the remains of many leaves and the whole caudex, except for 

 its smaller size, was very much like that of the adult plant. The broad vascular 

 strands made up of the confluent leaf traces formed an irregular circle which in 

 fig. 175, D, 2, 3, shows the free central strand which lower down forms the com- 

 missure across the central parenchyma. The arrangement of the bundles, therefore, 

 in the young plant of Marattiaceae is the same as in the adult rhizome oi Kaulfussia. 

 In these sections two roots are shown, one of which is cut through the point of 

 junction with a strand of the dictyostele (fig. 175, D, i). As in the younger germ 

 plants, tannin cells are quite absent from the stem, although in the roots they are 

 conspicuous. A few large mucilage ducts, however, occur in the ground tissue of 

 the stem. 



Farmer and Hill give one figure of a cross-section of the stele from the young 

 stem of Marattta which shows that it has essentially the same structure as that of 

 Dancea. There is a fairly well-marked endodermis, within which lies a broad zone 

 of phloem, entirely surrounding the central mass of xylem. 



According to Kiihn, there is in the older plant a second circle of bundles within 

 the first, but no satisfactory account is given as to the relation of the bundles making 

 up this second circle with those of the outer dictyostele. However, it is probably 

 composed also of elements derived from the leaf traces, but it is possible that some 

 of the strands may be of cauline origin. 



THE ADULT SPOROPHYTE OF MARATTIA. 



The genus Marattia includes about -25 extremely variable species, some of 

 which, e. g., M. fraxinea, closely resemble Angiopteris in their general habit (see 

 Bitter I, page 441; Christensen 1). They occur in the moist, tropical regions of 

 both the Old and New World, and one species, M. salici folia, extends as far south 

 as the Cape Region of South Africa. M. douglasit is a conspicuous fern of the 

 Hawaiian Islands. This species I have studied somewhat in detail, as well as the 

 West Indian M. alata, which is abundant in the mountain forests of Jamaica. These 

 two species closely resemble each other in general habit and have the leaves very 

 much more divided than is the case in M. fraxinea and its allies (see plate 12). 



The stem in the adult plant is an almost globular, upright caudex, a foot or 

 more in diameter in large plants. The closely set, spirally arranged leaves have 

 very stout petioles, 5 or 6 centimeters in diameter at their base, which is enlarged 

 and provided with two very large wing-like fleshy stipules, which, with the base of 

 the leaf, remain attached and completely cover the caudex after the petioles have 

 fallen away. There is at the base of the leaf, as in the other Marattiaceae, a pulvinus- 

 like enlargement, where the leaf breaks off, leaving a clean scar marked by the broken 

 ends of the vascular bundles. The leaves may reach a length of 2 to 3 meters or 

 13 



