MONOGRAPH OF THE BRITISH SPECIES OF EUPHRASIA. 823 



of process is of little specific importance ; it consists of shield-like 

 sessile glands found in all the species, especially on the under sides 

 of the leaves and bracts. 



The Root. — When the seed germinates, the primary root soon 

 emits smaller secondary roots in acropetal order, which at first, 

 though near together, are at regular distances apart, but later on 

 other roots intervene, which destroy any appearance of regularity. 



Both the main root and the secondary ones of all the annual 

 species are, taken as a whole, small, and occupy but a small area. 

 Hairs on the roots are few ; a ring of hairs is produced on the 

 young radicle soon after germination, and there are a few hairs at 

 the root-tips and on the haustoria. The character of the organs 

 termed haustoria is of special interest. They appear on the secondary 

 roots soon after the seed has germinated, but later on may occur 

 also on the main root ; they consist of a special discoid-like exo- 

 genous growth, which attaches itself to the roots of the plants on 

 which the species are parasitic, and from which nourishment is 

 derived. The roots are usually those of grasses and sedges, and 

 unless these are present haustoria are not produced, growth 

 becomes arrested for lack of parasitic nourishment, and though 

 the plant can grow stem, root, and a few leaves, it seems unable 

 to produce flowers and fruit, and eventually perishes. L. Koch has 

 written on the haustoria of Euphrasia in Pringsh. Jahrh. f. Wiss. 

 Bot. xxii. 1891, and references to other observers on the parasitic 

 growth of lihinantliacecB will be found in Prof. Wettstein's Monnrjraph, 

 p. 11. Prof. Wettstein has traced the growth of cultivated E. Rost- 

 koviana on the roots of Poa nemoraUs and P. annua, and on Agrostis 

 vuli/aris, on which plants the parasite thrived; he could not succeed 

 in bringing the parasite to perfection on Hulciis mollis or on 

 Cijperacete. He was only once able to trace the parasitic growth of 

 E. Salishurgensis on the roots of a Carex, and in culture he succeeded 

 in bringing plants to perfection on the roots of Carex alba. I myself 

 traced the growth of the haustoria of E. Scotica on the roots of 

 Ci/peracea ; the species were Carex flava, C. panicea, C. fulva, 

 C. i/laiica, and C. pulicaris, but I was unable to trace on which of 

 these the plant was parasitic. 



The Stem is usually branched, but in some species it is simple. 

 It is simple or branched in all British species. The position and 

 the wealth of the branches on the stem is of specific value. The 

 stem is green, or is often tinged with purple or red ; it is more or 

 less clothed with jointed recurved hairs, and in some species with 

 glands and glandular hairs; the character of these hairs and glands 

 has already been treated of. The branches are subopposite ; they 

 are simple, as in E. brevipila, E. (jracilis, E. carta, &.C., or compound, 

 as in E. nevwrosa. [E. Eoulaensis seems to be usually unbranched.) 



Leaves. — The cotyledons are, in all the species, simple, small, 

 rotund or egg-shaped, and entire. There is a remarkable di£ference 

 between the greater or less hairiness of these ; in E. liostkoviana, 

 which is a very hairy species, the cotyledons are hairless or nearly 

 so. The leaves are usually opposite, though the upper pairs are often 



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