MISCELLANEOUS PLANTS 



203 



hands of man. Its capacity in this respect is exemplified on Gibbs 

 Cay, where it grows on the dry sandy slopes of the island. On half 

 of the cays that form the Turks Group, namely, on Round Cay, 

 Penniston Cay, Pear Cay, Eastern Cay, and Greater Sand Cay, the 

 plant was not observed. 



The observations made by Mr. Lansing (and described by Dr. 

 Millspaugh) on the Florida sand-keys west of Key West, are of 

 interest in this connection, since the method of stocking newly 

 formed islands is there illustrated. Out of nineteen keys examined, 

 five displayed the plant; and it appears that where it is conspicu- 

 ously absent from a group of the keys, as in the Tortugas, this is 

 to be attributed to the fact that they lack the mangroves with which 

 this tree is usually associated. Yet it is rarely in great quantity on 

 any of these Florida sand-keys. Four out of the five possessing it 

 displayed only one or two moderate-sized colonies, and it was only 

 in the fifth that it was well represented. The station was nearly 

 always the same, namely, at the back of the vegetation of the exposed 

 sandy part of the islet and bordering the Avicennias that fringed the 

 great colonies of Rhizophoras. 



Although it would be wrong, as Schimper also observes (p. 64), 

 to number Conocarpus erectus with the mangroves, it would be equally 

 wrong to place it with the typical trees and shrubs that line the 

 sandy beach. From the standpoint of station it comes between 

 the two ; but in the matter of its distribution it has the range of the 

 mangroves and accompanies them almost everywhere. When I 

 first met with this plant on the coasts of Ecuador and Panama, 

 its double station appeared very puzzling. But I found that this 

 was recognised by Baron von Eggers, who, whilst studying the 

 Ecuadorian strand plants, placed Conocarpus erectus in different 

 localities in the mangrove formation and in the sandy-beach flora. 

 This is the dilemma in which the plant frequently places the botanist, 

 and it is one from which he can free himself by investigating the 

 stages of the plant- stocking of newly formed islets in these seas. 

 Such an inquiry has been accomplished in the case of the Florida 

 sand-keys by Mr. Lansing and Dr. Millspaugh. The last-named 

 botanist makes a special association for this locality of the plants 

 of the mangrove borders, including Avicennia nitida, Laguncularia 

 racemosa, Conocarpus erectus, etc.; and he shows how in the case 

 of a young Rhizophora colony, recently established on a newly formed 

 sand-key, Conocarpus erectus may take the place of the usual Lagun- 

 cularia fringe. 



The small scale-like achenes, which are gathered together in a 

 rounded cone-like fruit-head, readily become detached when the 

 head dries. They average about 4 mm. across and possess great 

 floating power. Although Schimper did not test their buoyant 

 capacity, he rightly postulated it from their structure (Ind. Mai. 

 Strand Flora, pp. 170, 180), which he compares with that of Ter- 

 minalia fruits of the same family. Within the thin, impervious, shell- 

 like outer skin there is an extensive development of spongy air- 

 bearing tissue, and within this is the seed protected by a hardened 

 layer of the endocarp. No part of the fruit or seed has any floating 



