556 



The Supplement to the Tropical Agriculturist 



The climate is fairly damp and rain falls during 

 five or six mouths of the year. The rainy season 

 commences about January ; heavy rains are not 

 frequent, but the rains are' more like those of 

 England, and there is a considerable amount of 

 damp mist. During the dry season no rain ever 

 falls, but mists and heavy dews prevail at night- 

 time. In the wet season the rivers rise about 20 

 ft. and fall some 2-3 ft. below their normal level 

 in the dry season. The soil of the plateau is 



A DEEP AND VERY SANDY LOAM. 



sandy loam of finely divided, clean black earth 

 four or more feet in depth. This soil retains 

 moisture readily though it never cakes or runs 

 together ; it is always very warm beneath the 

 surface, giving the impression that fermentation 

 is proceeding. It is possible to dig a hole with a 

 stick to a depth of three or four feet as in sand. 



The plateau is covered with a very fine grass, 

 growing to a height of not more than 2 ft., and 

 the Raphionacrne plants are found growing 

 plentifully among the grass. Off the concession 

 (plateau) the growth of the grass is very rank 

 and coarse, some 6 to 7 ft. high, and is almost 

 impossible to penetrate, 



The plants grow with the leaves closely pressed 

 to the surface of the ground, forming a kind of 

 rosette after the manner of plantains on a lawn. 

 The tubers usually occur buried just below the 

 surface of the soil, and may be shaped either 

 like a turnip or peg-top, or may be very broadly 

 napiform to discoid. They produce from 1 to 

 3 leafy shoots, each bearing 4 to 6 pairs of leaves, 

 and as a rule only one of the shoots produces 

 an inflorescence. The shoots are quite short but 

 in old plants the inflorescence may be born on a 

 longer stalk about 2 ins. in length. Unless 

 burnt by bush fires it appears that the leaves 

 remain green, and the tubers continue to grow 

 throughout the year. Of the tubers sent to 

 Kew by Mr Norman, the discoid ones were the 

 larger, and one of the specimens weighed 2 lb. 

 5 oz. Mr May, however, states that a large 

 number of the 



TUBERS WEIGH FROM 4—5 LBS. 



and he has found a specimen weighing as much 

 as 15 lb. It seems probable that there may be 

 more than one species of Raphionacrne growing 

 on the plateau, but whether the tubers of 

 different shapes belong to different species 

 cannot yet be determined. An inflorescence 

 borne by one of the discoid tubers proves this 

 plant to bo Raphionacrne utilis, though in the 

 general shape and colour of the leaves it differed 

 somewhat from the plant already described 

 (K. B., 1908, p. 215, and Bol. Mag. tab. 8221). 

 Mr May is inclined to believe that there are 

 probably five or six different kinds of rubber- 

 yielding tuboiB. One kind in particular bears 

 a much larger tuber than the true Ecanda 

 plant, and has finely cut leaves "like a tuft of 

 grass." In this plant the skin or rind of the 

 tuber is coarse like the bark of a tree, and the 



LATEX OCCURS ONLY IN THE RIND. 



In shape and size the tubers resemble a rugby 

 football. In the Ecanda plants the veins of the 

 leaves may or may not bo purple on the under 

 side. 



The floweis of R. utilish&ve already been des 

 cribed.but those of Mr May 's plant were of a deep 

 claret colour and borne in a torminal cluster. 



The plants usually flower on the plateau in 

 November and early December, the driest time 

 of the year, and the seed is ripened at about 

 the end of December, just before the com- 

 mencement of the rainy season. Seed is pro- 

 duced in quantity but it tends to be destroyed 

 in great part as the natives burn off the grass 

 among which the plants are growing j ust 

 before the rainy season sets in. 



THE COLLECTION OF THE SEED 



is difficult and to trade costs in goods the 

 equivalent of about 



£4 PER oz. 



The tubers are collected by the natives on the 

 plateau in the following manner. The fine grass 

 and general vegetation covering the country is 

 set on fire aud the tubers, which can then be 

 easily seen, are hoed up and brought to head- 

 quarters in baskets. Large and small tubers are 

 gathered indiscriminately, but the contents of 

 the baskets are weighed and sorted, and only 

 those of large size are kept for the production of 

 the rubber. The two illustrations from photo- 

 graphs, taken by Mr May on the concession 

 plateau, shew a quantity of the Ecanda tubers 

 brought in by the natives for the extraction of 

 the rubber. The smaller ones are thrown aside, 

 and as they are not materially damaged by the 

 burning of the grass, they are replanted and 

 commence to grow again quite readily. 



No attempt at the cultivation or clearing of 

 the ground has been attempted, nor have any 

 experiments been made with the sowing of seed. 

 In replanting the smaller tubers a hole is simply 

 dug in the earth amongst the grass with a native 

 hoe and the tuber is planted and 



LEFT TO GROW UNTENDED. 



As to the rate of growth of the tubers, it is un- 

 fortunate that at present we have no reliable in- 

 formation. According to Professor Geraldes 

 (K.B., 1908, p. 214) the plants are biennial (?), and 

 one-year old plants are stated to be about 3-4 ins. 

 in diameter, and to weigh from 7-10? ozs. Mr 

 May has not made any careful observation but 

 is of the opinion, however, that a three-year 

 old root would weigh about 6 ozs. As the na- 

 tives always burn the long grass once a year in 

 order to obtain fresh herbage, he thinks that 

 these fires may possibly check the growth of any 

 tubers over which thoy pass. We have been in- 

 formed that the yield of tubers, on an experi- 

 mental plantation in a neighbouring region, at 

 a minimum estimate is likely to be 8 tons, and 

 that there is every prospect that a yield of about 

 12 tons per acre will be realised. 



Seedlings of Raihionacme Utilis. 

 In connection with the question of the rate of 

 growth of the Ecanda plant the behaviour of 

 some seedlings raised in the Royal Botanic Oar- 

 dens, Kew, is of some interest. At the end of Dec. - 

 1908, a parcel of Ecanda seed was received from 

 the Anglo-Angolese Trading Co., Benguella, 9, 

 Billiter Street, London, E.C., with the follow- 

 ing note : " Seeds of the Ecanda tuber, called 

 also ' Vitiuga' or 'B'tiuga' plant by (he Angolese 



