63 



During Great Britain's South African War (1899-1901), a 

 large number of mules was brought over from Texas and South 

 America to Africa for transport purposes for the troops, and for 

 repatriation work; subsequently, in the neighbourhood of the 

 artillery and repatriation camps, plants of M. louisiana were 

 occasionally found, having grown, apparently, from seed which 

 had fallen from capsules included in the hay brought with the 

 mules; or, it may be, from capsules still entangled, by means 

 of their tenacious hooked spines and curved horns, in the tails 

 of the animals. 



Knight and Step, in a semi-popular work on "The Living 

 Plant," 1 quote Frank Buckland as saying that the fruits of 

 Martynia louisiana must have been created ' 'for the express pur- 

 pose of sticking to the tails of the wild horses which roam the 

 plains of South America." Dr. Burtt Davy's observations in 

 South Africa, however, suggest that the structure of the fruit 

 provides a seed-distribution mechanism much more perfect and 

 less fortuitous than that brought about by the mere transport 

 of the capsules in the tails of animals, in which they might, or 

 might not, hang in a position suitable for the scattering of the 

 seeds. 



It will be noted in Fig. 1, how the mature fruit lies upon 

 the ground, with its two curved horns directed upwards and 

 backwards. The horns are springy and resilient, and should an 

 animal tread upon the fruit as it lies in its natural position, its 

 fetlock is immediately gripped by the horns. As the animal lifts 

 its foot, the horns cause the body of the capsule to spring back- 

 wards, so that the prominent ridge of hooked spines or bristles 

 comes into sharp contact with the fetlock, to which the capsule 

 thus becomes firmly attached, in such a position that its open- 

 ing is directed downwards. The retrorse bristles, of course, pre- 

 vent the capsules from falling off; in fact, they tend to cause it to 

 work up the animal's leg. As the animal walks away, carrying 

 the fruit thus attached, the seeds are gradually scattered. 



Observations of this seed-dispersal mechanism have en- 

 dowed the plant with still another common name, peculiar to 

 South Africa, namely, "mule-grab." 



1 Knight, A. E., and Step, E. "The Living Plant in Leaf, Flower and 

 Fruit." London, Hutchinson, 1905. P. 363. 



