174 On the Orobanche and Prunella vulgaris. 



roots of the common broom, and in fields on the roots of clover. 

 In their first appearance they resemble, in some measure, the 

 shoots of asparagus just as they break through the ground. The 

 stems rise from six to ten inches high, and without proper leaves, 

 having what are called bractes instead. The flowers are arranged 

 on the stem, like those of a hyacinth, but not so show^, being of 

 a dingy-brown colour, succeeded by oblong capsules of seeds, A 

 straggling individual plant is sometimes met with among ley-wheat 

 feeding on a clover plant which has escaped destruction by the 

 plough and harrow at wheat sowing ; but it never appears again 

 till the field is re-sown with clover. 



It is not easy to account for this last-mentioned circumstance^ 

 except only by supposing that the seeds are capable of remaining 

 unhurt in the soil for four, five, or more years, or that they are 

 sown with the clover. 



I have long been inclined to entertain the latter opinion, and 

 for the following reasons : the weed always appears most plenti- 

 fully on the second crop, and this crop in the south of England is 

 that which is chosen for yielding seed. Of course, the weeds and 

 clover are mowed, carried, thrashed and cleaned together. The 

 seeds of both ripen about the same time, and when mixed toge- 

 ther are not easily distinguished without a knowledge of the forms 

 of each, and the assistance of a magnifying glass ; but examined 

 apart they are visibly different. The seeds of the broom-rape are 

 like those of clover, only not so plump ; neither so large nor so 

 glossy, the skin being rough and of greyish colour. 



In cleaning clover seed very fine chip or wire sieves are used, 

 but neither of these are fine enough to separate the smaller seeds 

 of the parasite from those of clover. But sieves may be woven so 

 fine as to separate them, without much loss of the clover-seed ; and 

 these should be ordered from the sieve wright and used by the 

 grower, and particularly by the seedsman. Both should be well 

 acquainted with the forms of the seeds, so as to identify them at 

 sight. Gathering and keeping a sample of the seed of the parasite 

 is an easy matter, and which may be kept for reference. 



There is another British plant which is also too frequently seen 

 on clover leys, and which, from its casual appearance on arable 

 land, must have been saved, and sown with the clover. It has 

 some distant resemblance to clover in the colour of the flower, but, 

 botanically considered, is of a very different genus — I mean the 

 common self-heal (Primella vulgaris) ; it flowers and ripens seeds 

 along with the seed- clover crop, and it is more than probable that 

 the seeds are mixed in the dressing. As, however, the seeds of the 

 self-heal are smaller than those of clover, they may be riddled out 

 by a properly made sieve. 



