22 Evans : Hepaticae of Puerto Rico 



connate on one side with bract, broadly ovate to obovate, 0.85 

 mm. long, 0.6 mm. wide, apex broad, retuse to shortly bidentate, 

 margin as in the leaves ; perianth immersed in the involucre or 

 slightly exserted, obovoid, 1 mm. long, 0.6 mm. wide, narrowed 

 toward the base, broad and rounded at the apex and with a very 

 short beak, sharply five-keeled especially toward apex, surface 

 roughened from projecting cells especially along the keels : $ 

 inflorescence occupying a short branch or more rarely terminal on 

 a microphyllous branch ; bracts mostly in from three to six pairs, 

 closely imbricated, strongly inflated, shortly and subequally bifid 

 with an arched keel, the lobe rounded, the lobule sometimes sub- 

 acute or apiculate at the apex ; bracteoles one or two at the base 

 of the spike, similar to the underleaves but smaller ; antheridia in 

 pairs : mature sporophyte not seen (plate 2, figures 9-23). 



On bark of trees. North slope of the Luquillo Mountains, 

 Heller (4.739). El Yunque, Evans {73). The type specimens were 

 collected in Puerto Rico by Schwariecke. The species has also 

 been found in Jamaica, Underwood, Maxo?t } Evans. 



An interesting feature of P. Schwaneckei is found in the 

 peculiar microphyllous branches, which are usually abundantly 

 developed on both male and female individuals (figures 9, II, 12). 

 These branches are nearly always completely concealed by the 

 leaves and are therefore invisible when a stem is viewed from above. 

 Although so short, each branch bears from three to seven pairs 

 of closely imbricated leaves with corresponding underleaves. The 

 leaves are very much smaller than ordinary leaves and measure 

 about 0.2 mm. in length ; they are shortly bifid, the lobe being 

 but little larger than the lobule, and the keel is strongly arched. 

 The lobe is suberect and rounded at the apex, and its margin is 

 vaguely angular-dentate. The lobule is inflated and blunt at the 

 apex, being similar in this respect to normal lobules. The small 



i 



underleaves are essentially like those found on the stem. Appa- 

 rently these microphyllous branches increase the water-holding 

 power of the plants, partly by means of their protected position, 

 partly by means of the close imbrication of all their parts. They 

 apparently assist also in affixing the plants to the substratum, since 

 rhizoids are abundantly produced by their underleaves.* 



* Similar microphyllous branches occur in Radida pycnolejeuneoides Schiffn., from 

 the island of Amboina (Nova Acta Acad. Caes. Leop. -Carol. 60: 247. pi. ij f /.i-y. 

 1893). They were originally described as male spikes, but their true nature was soon 

 pointed out by Goebel (Flora 77 : 432. //. 8, g. f. j 9 4. 1893). 



