332 
KEYS TO THE FERNS OF BORNEO 
15. PTERIDIUM Gleditsch. 
P. aquilinum (L.) Kuhn. 
Common. 
Cosmopolitan. 
16. HISTIOPTERIS (Agardh) J. Smith. 
a. Pinnules ample, entire. 
b. Axillare leaflets (“stipules”) none or 
inconspicuous i. H. integrifolia 
fci. “Stipules” conspicuous 2. H. stipulacea. 
tfi. Pinnules smaller, deeply lobed 3. H. iticisa. 
1. H. INTEGRIFOLIA Copel. 
Sarawak, North Borneo. 
Endemic. 
2. H. stipulacea (Hooker) Copel. 
Sarawak. 
Endemic. 
3. H. incisa (Thunb.) J. Sm. 
Sarawak, North Borneo. 
Tropics and beyond them. 
Bonaparte mentions a var. “ aurita-integrifolia.’ 
17 . PTERIS Linm/eus. 
a. Veins free. 
b. Pinnas simple, or the lowest pair once 
forked. 
c. Pinnae numerous, uniform 1. P. longifolia. 
U. Pinnae few. 
d. Pinnae thin, sterile margin wavy or 
toothed 2. P.pellucida. 
d*. Pinnae thick, entire 3. P. rangiferina 
b r. Pinnae not mostly simple, but not pectin¬ 
ate, dimorphous 4. P. ensiformis. 
b 2. Pinnae regularly lobed or divided, chiefly 
on the lower side 5. P. semipinnata 
b 3 . All pinnae pectinately divided or pinnate. 
c. Stipes not nearly black. 
d . Lateral pinnae only one forked pair 6. P. grevilleana . 
di. Lateral pinnae more numerous. 
