182 CLIMBING PARASITES. GREEN-LEAVED PARASITES. TOOTH WORT. 



The seed of Lathroea germinates on damp earth. The young root of the seedhng 

 grows at first at the expense of reserve material stored in the seed, penetrates 

 vertically into the earth and sends out lateral branches, which, like the main root, 

 follow a serpentine course and search in the loose damp earth for a suitable nutrient 

 substratum. If one of these meets with a living root belonging to an ash, poplar, 

 hornbeam, hazel, or other angiospermous tree, it fastens on to it at once and 

 develops suckers at the points of contact; these suckers are at first shaped like 

 spherical buttons, but soon acquire, as their size increases, the form of discs 

 adherent to the host's root by the flattened side and with the convex hemispherical 

 side turned towards the rootlet of the parasite. These discoid suckers cling to the 

 root attacked by means of a viscid substance produced by the outermost layer of 

 cells. As in the case of the parasites already described, a bundle of absorption-cells 

 grows out of the core of each sucker into the root of the plant serving as host, and 

 the tips of the absorbent cells reach to the wood of the root. The shoot extremity 

 of the seedling, thus nourished by the juices of the host, now develops very quickly, 

 elongating and producing thick, white, fleshy, scale-like leaves which overlap one 

 another closely, the whole thus acquiring the appearance of an open fir-cone. The 

 scaly stems also branch underground, and thus a curious structure is gradually 

 produced, consisting of crossed and entangled cone-like shoots covered with white 

 scales, and this structure fills entirely the nooks and corners between the woody 

 roots on which it preys. Individual plants extending over a square meter and 

 weighing 5 kilograms are by no means rare. Later on, inflorescences raise them- 

 selves above the surface from the extremities of the scaly subterranean shoots. 

 Their axes are at first curved like crooks, but straighten themselves out by the 

 time the fruit ripens. Whereas the subterranean portions are white as ivory, the 

 flowers and bracts pushed up above the earth are of a purplish tinge. The roots, 

 which issued originally from the seedling, and their suckers have long since ceased 

 to meet the requirements in respect of nourishment of so greatly augmented a 

 structure, and therefore additional adventitious roots are produced every year, 

 springing from the stem and growing towards living woody branches of the 

 thickness of a finger, belonging to the root of the tree or shrub that serves as host. 

 When there, they bifurcate, forming numerous thickish filiform arms, which lay 

 themselves upon the bark of the nutrient root and weave a regular web over it. 

 Sometimes two or three of these root-filaments of the parasite coalesce, forming 

 tendrils, and the resemblance to a lace-work or braid is then all the more 

 pronounced. Suckers such as have been described are developed by these root- 

 filaments laterally, and more especially on the ends of the branches. 



Lathroea is interesting in so many different connections that we shall again 

 return to this plant later on. As has been stated before, it affords a type of a series 

 of parasites which resembles the species of Cassytka and Cuscuta in the absence of 

 chlorophyll, Rhinanthacese in the shape and development of the seedling and the 

 form of the suckers, and the Balanophorese, presently to be described, in being 

 parasitic upon the roots of woody plants. Lathrwa Squamaria, the species repre- 



