244 UNDERWOOD: AMERICAN FERNS 
Stems simply pinnatifid or pinnate.* 
Sori borne on the ends of ordinary veins ; rootstocks creeping. PLATYZOMA. 
Sori borne on horseshoe-shaped receptacles ; rootstocks erect. STROMATOPTERIS. 
Stems pseudo-dichotomous, once to many times forking. 
Sori borne on the ends of veins; segments in the form of 
unded lob LEICHENIA 
Sori borne dorsally on the veins or at a fork ; pinnae pectinate. DICRANOPTERIS. 
Of the above genera Dicranopteris is found in both the Old 
World and the New, extending in range from Japan to the Straits 
of Magellan. The other genera are confined to the southern 
hemisphere of the Old World. As stated above Platyzoma and 
Stromatopteris are monotypic, while Gleichenia has several species 
ranging from South Africa to Java and Australia.t The species 
of Gleichenia are frequent in cultivation in the conservatories of 
the Old World, but we have never seen any of the species of Dr 
cranopterts in cultivation anywhere. The development of the 
sexual stage is only incompletely known, having been partially 
studied by Rauwenhoff, ¢ but in Jamaica at least the early stages 
of several species are abundant on the clay banks from germinating 
Spores to young sporophytes in all stages. The young stages of 
the various species could profitably be studied at the Cinchona 
laboratory, as all four of Diels’ sections of the genus are abun- 
dantly represented within easy reach of that station. 
ome of the larger members of the genus Dicranopteris form 
thickets so deep that we have seen tunnels cut through them in 
which men could walk erect, and once, at Tweedside, Jamaica, 
Mr. Maxon and the writer walked for more than half a kilometer 
on the bent-down branches of tangles that had overgrown an 
unused bridle-path, our guides, tired of cutting paths, forcibly throw- 
ing themselves upon the tangles and we following on the springing 
elastic masses never once touching the ground and often a meter 
or more above it. Nearly all the species show a pseudodichotomy, 
and in each fork the growing axis remains in the form of a dor- 
mant bud ready to spring up as soon as the necessities of the plant 
demand additional foliar expansion. The accompanying diagram 
Sn ee ee 
* One of the South American species of the genus Dicranopteris has simple pes 
tinate stems. Too little is known of the species, however, to base any conclusions on It- 
others, 
tN. P. W. Rauwennorr: La génération sexuée des Gleicheniacées. Arch. 
Néerl. 24: 157-231. pl. 4-10. 1890, 
T In Synopsis Filicum six species of 4 Lugleichenia are recognised, but there are 
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