CHAP. XV AN AUSTRALIAN IMMIGRANT 285 



species of wild date {Phcenix sp.), known to the Zanzibari as 

 the " mkindu " (from which the river to the north of Kibwezi 

 takes its name), and a water palm {Raffia sp.), both of which 

 occur along the rivers of Kikuyu and Ukamba. 



After the palms, the mangroves (mainly belonging to the 

 species Rhi^^opJiora imicronata, Lam., and Bruguiera gyninor- 

 rhiza, L.) form the most striking feature in the coast flora. They 

 grow in dense, jungly masses, bordering the estuaries and tidal 

 creeks. The trees usually grow in the water, but the whole of 

 the trunk is raised above it by a series of adventitious roots ; 

 it therefore appears as if the tree were supported on a many- 

 legged stand. The most interesting point about the plant is 

 the method by which it prevents its seeds falling by the way- 

 side, and restricts them within the narrow belt in which alone 

 they can grow. If the seeds were scattered on the surface 

 of the estuary, the currents would either cast them ashore or 

 wash them into water too deep for them to root in. The seeds 

 therefore germinate while attached to the tree. The radicle 

 grows into a thick solid spike, eight or ten inches in length, 

 which, when released from its attachment to the parent, falls 

 with sufficient force to drive the spike firmly into the mud 

 beneath. The seeds therefore secure a suitable soil, and stow 

 into dense thickets along the shore between the tide lines. 



A third conspicuous feature in the coast flora came rather 

 as a surprise. In front of the Residency at Lamu there are 

 some specimens of that typically Australian tree, the She-Oak or 

 Casiiarhia. These had obviously been planted artificially, so 

 I thought no more of the matter. But on returning to the 

 coast at Marereni, there we found on the headland a clump of 

 these graceful feathery trees. Subsequently I noticed them in 

 similar positions at all the points on the coast where I landed, 

 as far south as Natal. The Suahili proverb, quoted on p. 237, 

 shows that the natives have noticed the very restricted belt in 

 which the she-oak can live, for Kisauni is on an estuary about 

 a mile from the sea : their cones must have been carried from 

 Australia by the West Australian and the " Equatorial Drift " 

 currents, and washed upon the shore. They thus form an im- 

 pressive lesson on the action of the sea as an agent in plant 

 distribution, 



2. The Foot-hills. — Accepting the palms and the man- 



