430 swingle: new genus pleiospermium 



It is possible that this plant is identical with the enigmatic Limonia 

 diphylla published in 1774 by Houttuyn, who received a twig collected 

 by Richter at Batavia, where it is said to produce fruits resembling 

 limes ("regte Limmetjes of Lemisjes"), the size of a pigeon's egg, on 

 spiny twigs. The leaves are said to be paired on the same petiole. 

 Houttuyn's plate shows a twig with 3 binate leaves with obtuse 

 leaflets, one small unifoliolate leaf, and a small terminal flower with 

 4 petals and 8 stamens. The figure seems to be diagrammatic and was 

 probably drawn from poor material. The plant is said to be called 

 Crandang by the Javanese. 



It may be that Houttuyn's species was founded in part on Richter's 

 account of a true lime, Citrus aurantijolia (Christm.) Swing., and in 

 part on a twig which he brought to Holland from Batavia, possibly 

 from some very different plant, such as a Bauhinia. It seems impos- 

 sible to decide the matter unless Houttuyn's type can be found. 



Pleiospermium dubium seems to be rather close to P. alata, but has 

 the leaflets acute, instead of obtuse, and many leaves with only 1 or 

 2 leaflets instead of 3-, as is common in P. alata; also it has the ovaries 

 pubescent instead of smooth, as figured in the Indian species. It is 

 said to be a small tree 3.5-4 meters high, with a twisted trunk branch- 

 ing at 1.5 meters and suckers from the base. It is called Kidjeroekan 

 in Java. 



In its foliar characters this is one of the most polymorphic species 

 among all the relatives of Citrus. The leaves are simple or 2- or 3- 

 foliolate, sometimes all three forms occurring on the same branch. 

 The petioles are sometimes very short and sometimes rather long, 

 sometimes plainly winged, often nearly wingless. The spines are 

 sometimes single, sometimes paired, and often entirely wanting. It 

 is undoubtedly one of the most primitive of all the citrous plants, 

 showing as it does striking analogies with plants belonging to at least 

 three distinct subtribes. 



The fruits of this species show small and slender pulp vesicles aris- 

 ing from the inner ovary wall 2 to 3 or even 4 mm. long. It is not 

 known whether P. alatum also has such rudimentary pulp vesicles. 

 Both species have fruits filled with dark-colored, strong-smelling, 

 mucilaginous gum. 



POSSIBLE UTILIZATION OF PLEIOSPERMIUM 



From the fact that Pleiospermium alatum grows abundantly 

 in the dryer parts of Ceylon it would be desirable to test it as 



