27 
Ridley .— The Distribution of Plants. 
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The large artificial lake in the Botanic Gardens in Singapore contained 
a number of aquatic plants which were certainly not planted there, and 
which did not, as far as I know, occur in any spot whence they could have 
been drifted into the lake. They were Enhydrias angustipetala , Ridl., 
Blyxa malayana , Ridl. (Hydrocharideae), Naias graminea, Del., a Char a, and 
two Utricularias. I have little doubt that these were brought from con¬ 
siderable distances by wading birds or ducks. A lake like this in a country 
where ponds and pools are extremely scarce is always very attractive to 
birds on migration, and ducks, jacanas, sandpipers, and even cormorants 
have appeared from time to time on this pond. 
It will be noticed that a considerable proportion of the most widely 
distributed species of plants are Cyperaceae and Gramineae, wind-fertilized 
plants which do not require pollination by insects, and I would suggest that 
this has a considerable bearing on the rapid distribution and the large 
number of plants of one species occurring together, often over considerable 
areas such as the extensive tracts of Imperata arundinacea , Cyr., Chryso- 
pogon aciculatus , Trin., the dense masses of Paspalum conjugation, Berg., 
along mountain paths, the large swamps almost entirely of Eleocharis 
eqmsetina , Presl., in Setul. I have never seen in the Malay Peninsula large 
areas of any single species of insect-fertilized plant, except the single-tree 
forests of Dryobalanops and of Avicennia , with which I will deal elsewhere. 
/ 
Of the Wide Distribution of Orders of Plants. 
In'Journ. Linn. Soc.\ xliv,p. 439, Mr. Guppy, in a paper entitled ‘Plant 
Distribution from the Standpoint of an Idealist’, suggested that orders were 
evolved first, then genera, then species. It is difficult to see how an order, 
an accumulation of species, could in the first instance be evolved before the 
species. The larger orders seem, from what we know of Eocene plants and from 
the story of distribution, to have appeared at an early date, such orders, that 
is, as Anonaceae, Laurineae, Leguminosae, and Myrtaceae, but that all orders, 
even large ones, were evolved before the genera is very easily disproved. 
We have in tropical Asia a number of genera which are wanting in 
Australia and Polynesia, but which extend to Africa and are again well 
represented in South America. They have received no assistance from man, 
and are not widely dispersed by birds or by sea. Such genera are Tetracera 
(Dilleniaceae) and Xylopia (Anonaceae), and we have even one species, 
Pothoniorphe peltata. Now the only way these plants could have crossed 
the ocean from Africa to South America is by a former land connexion 
such as is shown in Arldt’s maps. This land connexion is believed to have 
broken down before the Pliocene period, and these plants must have crossed 
before that. Now in South America we have two big, besides several small, 
orders peculiar to that country which have even better means of dispersal 
