i53 
HERBS {RHIZOMES) 
Monotropa, Linaria, &c., the main root is fleshy and each new annual 
shoot arises at its summit, sometimes in the axil of one of the leaves of 
the preceding year, sometimes as an adventitious bud. 
Other plants store reserves in underground creeping stems or 
rhizomes. These are usually thickened ; their leaves are reduced to 
scales, being useless for assimilation purposes. In a few cases the 
rhizome is monopodial (p. 42) and the leaves appear above ground, the 
stem remaining below, as in Pteris, but as a rule the rhizome is 
sympodial and each year’s shoot is of an L shape, its upper end 
appearing above ground and producing green leaves. Rhizomes often 
branch largely, and as the older parts decay the branches are set free 
and thus vegetative multiplication occurs. Good examples are seen in 
Iridaceae, Juncus, Musa, Dioscorea, Cyperaceae, Oxalis, Helleborus, 
Sanguinaria, and many other plants. In some cases the rhizome 
instead of creeping horizontally stands more or less erect and resembles 
a tuber ; in such cases it is usually termed a root-stock, e.g. Aspidium 
(monopodial), Primula (sympodial). All these types graduate into one 
another imperceptibly. 
Other shoots occur whose chief or sole function is vegetative 
reproduction, rather than hibernation. In Gesneraceae, short rhizomes 
or suckers are formed as branches which turn up at the end and form 
new plants ; these ultimately become detached from the parent plant. 
Creeping stems (runners or stolons) occur above ground in many plants ; 
they are usually formed as axillary branches on the main stem near the 
base; they grow along the soil and take root at the nodes, and the 
axillary buds at the nodes form new plants, e.g. in the strawberry 
(Fragaria), Ranunculus sp., Agrostis, Agropyron sp., Epilobium sp., 
Nephrolepis, Ajuga, and others. In Glaux, Samolus, Nasturtium, &c., 
new shoots are formed and take root, but can hardly be called runners. 
The short runners of Sempervivum, Agave, &c., which bend up at the 
ends into new plants, are called offsets. Vegetative reproduction is also 
common in the upper part of the stem, especially in the inflorescence 
portion, where some or even all of the flowers are replaced by 
bulbils, &c. (see p. 113). 
Bud-protection (p. 41) is exhibited in many forms in 
herbs. Those which have to survive a winter usually have 
their buds, as we have just seen, upon underground parts, 
and thus little further protection is required ; this is given 
by the formation of scales (modified leaves or stipules) on 
the outside of the bud. Xerophytes and tropical plants, 
which require protection against drought and heat, are dealt 
with below. 
Protection against grazing animals is obtained in many 
herbs by aid of stinging hairs (Urticaceae, Loasaceae, &c.), 
prickles, spines, &c., or by the presence in the tissues of 
poisonous or distasteful substances. These also act as pro- 
