32 MANGROVE SWAMPS 
6. Carpels distinct, at least below, sometimes united at apex by 
the styles; plants with milky juice. 
Family 13, Apocynaceae; Cerbera. 
6. Carpels entirely united; plants with watery juice. 
7. Fruits drupaceous; flowers small. 
Family 14, Verbenaceae; Avicennia. 
7. Fruits capsular, dehiscent; flowers large. 
Family 15, Acanthaceae; Acanthus. 
4. Ovary inferior. 
5. Flowers not in dense heads; leaves opposite. 
Family 16, Rubiaceae; Scyphiphora. 
5. Flowers in dense heads; leaves alternate. 
Family 17, Compositae; Pluchea. 
DESCRIPTION OF SPECIES 
Family 1, POLYPODIACEAE 
Genus ACROSTICHUM 
ACROSTICHUM AUREUM Linn. (Plate VIII). LAGOLO. 
Local names: Piai (Agusan) ; pakupakian (Manila); lapole (Tayabas). 
Acrostichum aureum occurs in great abundance on open mud 
flats in the swamp and along tidal streams. The leaves are 
pinnate, leathery, and from 50 to 200 centimeters in length. The 
leaflets are from 20 to 50 centimeters long and from 4 to 6 
centimeters wide. Acrostichum aureum is distributed in the 
tropics of both hemispheres. 
Family 2, PALMAE 
Key to the genera. 
Stemless, with underground rhizomes; without spines.....................--.---- Nipa. 
Trunks erect with numerous, long, slender spines........................ Oncosperma. 
Genus NIPA 
NIPA FRUTICANS Wurmb. (Plates IX, X). Nipa. 
Local names: Sasd, ldsa, pduid (Tagalog) ; séga (Sambali) ; tata, anipa 
(Cagayan); nipa (Bikol). 
This palm is at once distinguished from all others in the Philip- 
pines by its habit and habitat. It occurs along tidal streams 
throughout the Philippines and, from an economic standpoint, 
is one of the most important palms in the Archipelago. It is 
of special interest from the fact that it thrives only in brackish 
swamps. Nipa has a stout, creeping, subterranean stem or 
rhizome. The leaves are pinnate, 7 meters or more in length, 
and occur in erect clusters. Nipa frequently forms a dense 
mass of vegetation which is very difficult to penetrate. The 
