RIVER AND STRAND VEGETATION. 53 
which form dense thickets and extend far out into the water at high 
tide. Among those which send down aerial roots into the mud are 
Rhizophora mucronata (Pl. UXIV) and Bruguiera qgymnorhiza (PI. 
XL), both of which have large, opposite, entire, smooth leaves, and 
fruit which germinates before dropping from the tree. They are easily 
distinguished, the former having a four-parted perianth and the latter 
having 10 to 14 calyx segments and petals. Associated with these are 
found red-flowered Lumnitzeras, small trees belonging to the Combre- 
taceae; Lylocarpus granatum (Carapa moluecensis), known in the 
Kast Indies as the ‘*cannon-ball tree,” on account of its hard, spherical 
fruits; and on adjacent firmer ground, Hieoecaria agallocha, some- 
times called the ‘‘milky mangrove” or the ‘‘ blinding tree,” the acrid 
juice of which is called ‘tigers milk” in the East Indies. 
RIVERS. 
Near the mouths of most of the rivers, where the water is brackish, 
are thickets of Nypa fruticans, a stemless palm with great pinnate 
leaves, which furnish the natives with excellent material for thatching 
their houses. Associated with it are large simply pinnate ferns, 
Acrostichum aureum (Pl. IV), of wide distribution throughout the 
warmer regions of the globe, and growing submerged are species of 
Potamogeton and Ruppia maritima. There are also green, filamentous 
alow, including species of Conferva and Enteromorpha, and Chara 
jibrosa. Near the sources of some of the streams a small red alga 
(Thorea gaudichaudi) isfound growing to rocks. On the banks of the 
rivers near the sea beds of Paneratium littorale occur, together with a 
creeping aroid, Cocos nucifera, screw pines, and Lurite tiliacewin. 
Higher up the stream there are beds of reeds (Trichoon) and, on the 
open hillsides, the sword grass, X¢pheagrostis foridula, Wherestreams 
flow through shady forests several cordate-leaved aroids occur, together 
with a tree fern (Alsophila haenke’) and the widely spread Angiop- 
teris evecta (Pl. X XXIII). 
THE STRAND. 
The principal beach plant is Jpomoea pes-caprae, often called ‘* goats- 
foot convolvulus,” from the shape of its leaves. Its long, prostrate 
stems forma carpet over the sand without twining or taking root, 
and bear large, rose-purple, funnel-shaped flowers. Associated with 
it is the leguminous Canavald obtusifolimm, with a similar habit of 
growth, and frequently Melastoma marianum, Vigna lutea, and TTelio- 
tropium curassavicum, Among the beach shrubs are Lobelia koenig/?, 
with thick, glabrous leaves, and white, zygomorphous flowers; 7ouwrne- 
Sortia argentea (Pl. LX VIII), a boraginaceous plant with fleshy leaves, 
covered with silky white hairs, and white, heliotrope-like flowers with 
dark anthers growing in scorpioid racemes; and /’%mphis acidula, a 
