THE oldi:r sporophvtk 



177 



sporophyte in D. jamaicensis and D. elltpttca are due to further branching of the 

 primary medullary strand, or whether some of them may be new bundles of cauline 

 origin, remains to be investigated. 



The arrangement of the characteristic mucilage ducts is the same in the two species 

 studied. There is a ring of these in the outer region of the cortex and a second group 

 in the central region, these central ones usually being close to the vascular bundles. 



Fig. 161. 



A. Section of adult rhizome of Danaa jamaicensis. X2.25 



B. Section of rhizome of D. elliptica. X1.5. 



The mucilage ducts are not shown. 



THE ANATOMY OF THE LEAF. 



A section of the petiole of the adult leaf appears very much like a similar section 

 of the stem, except that there is developed in the cortical region, separated by several 

 rows of cells from the epidermis, a band of sclerenchyma, yellowish or brownish 

 in color, and very much indeed like that common in the typical ferns. Holle's 

 statement that a similar mantle of sclerenchyma occurs in the stem was shown to 

 be an error, the result of his having investi- 

 gated a fern which was not a Dan&a. 

 There certainly was no trace of scleren- 

 chyma in any of the specimens I have 

 examined. 



The distribution of the vascular bun- 

 dles in the petiole is very similar to that in 

 Hclmtnthostachys, except that inside the 

 ring of bundles there is a single larger 

 centra] one, instead of the two small ones 

 which occur in Helminthostachys. All the 

 bundles are continued into the stem as 

 separate strands or there may be a certain 

 amount of anastomosing among them, as 

 there is in Ophioglossum pendulum, which 

 Datura resembles more in the character of its leaf traces than it does Helmin- 

 thostachys, where the bundles of the petiole are united into a single trace within 

 the cortex of the stem. 



The distribution of the mucilage ducts in the petiole is very much like that of 

 the stem. There is a definite ring of these inside the zone of sclerenchyma and several 

 larger ones in the central region, near the vascular bundles. The form and venation 

 of the leaf is essentially the same as in the younger sporophytes which have already 

 been described, and stomata are developed only upon the lower side, the epidermal 

 cells showing a strongly undulate outline, except for the series of narrow cells which 

 12 



Fig. 162. — Apex oi small root of Danaa jenmani. 



