COVERINGS OF SEEDS 251 



2. The testa is nearly always firm and tough. 

 In some cases, as in the Beans, it is particularly tough 

 and almost waterproof. In the Castor it is, on the 

 other hand, very hard and smooth and has peculiar 

 markings on it. In ARGEMONE and others of the 

 Poppy family, it is rough (pitted) in other cases it is 

 wrinkled. In some cases it becomes slimy and sticky 

 when wetted, e.g. in RUELLIA, PLANTAGO (sometimes 

 used on this account as a cure for dysentery) and 

 LINUM (flax). In the MALVACEAE it is often covered all 

 over with fine hairs (e.g. cotton) in others hair develops 

 only from one end. This we shall refer to later on. 



In addition to the two integuments which cover 

 the whole seed, and become its seed-coat or testa, 

 there develops on the seed of some species, another 

 outgrowth from the basal end. This which is termed 

 the aril, is different from the seed-coat proper, in 

 being usually soft (fleshy) and in not covering the 

 whole seed. On young seeds of PITHECOLOBIUM 

 DULCE (korukapulai), for instance, it grows irregularly 

 over the seed and is yellowish white in colour. In 

 MYRISTICA, the Nutmeg, it is red and forms a very 

 conspicuous irregular coating to the seed. 



In NYMPH^EA, the Water lily, the covering is almost 

 complete, while in the Litchi fruit, what we eat 

 is the thick fleshy aril that covers the whole seed 

 (underneath the brittle pericarp). An aril of some 

 kind or another occurs in many species of the fami- 

 lies SAPINDACE^ and CELASTRINE.E, in POLYGALA 

 ARILLATA (of the hills), and in other plants. The 

 seed of RiciNUS, the Castor, has a small hard aril 

 (sometimes called the caruncle) near the micropyle. 



