This compound word is baffling to me. The best I can make of it is “brake amidst the filberts”, i.e., a bracken or thicket of ferns around and under a woods of filbert or hazelnut trees. No literature I have found so far suggests these two plants associate often enough to have created a standard compound like “filbert-brake,” so I count this as a unique product of Tolkien’s wordcraft, pending correction.. – October 2005.
Hazelnut or wild filbert, Corylus species. Description: Hazelnuts grow on bushes 1.8 to 3.6 meters high. The nut itself grows in a very bristly husk that conspicuously contracts above the nut into a long neck. The different species vary in this respect as to size and shape.
Habitat and Distribution: Hazelnuts are found in the U.S. and also in Europe where they are known as filberts. The hazelnut usually grows in the dense thickets along stream banks and open places. They are not plants of the dense forest.
Edible Parts: Hazelnuts ripen in the autumn when you can crack them open and eat the kernel. The dried nut is extremely delicious.
Bracken or brake, common name for a tall fern (Pteridium aquilinum) with large triangular fronds, widespread throughout the world, often as a weed. It is considered poisonous to livestock when eaten in quantity, but the rootstocks and the young shoots, cooked, are used for food. A beverage is made from the roots. The names bracken and brake are sometimes also applied to other large, coarse ferns and, as general terms, to a thicket of such plants.