The roots of our grasses are almost always thin and _fibrous_ and are adventitious from the nodes, frequently forming radiating crowns round the base and easily pulled up, and usually broken in the process; but in the case of a few moor grasses--especially _Nardus_ (Fig. 2) and _Molinia_--the roots are so tough and thick (_stringy_) as to resist breakage very efficiently. In stoloniferous grasses a similar difficulty of removal may be caused in a slighter degree by the underground stems. In a few cases, e.g. _Alopecurus bulbosus_ (Fig. 3), _Poa bulbosa_, _Phleum pratense_ and _P. Bœhmeri_, _Arrhenatherum avenaceum_, and to a slighter extent in _Poa alpina_ and one or two others, the lowermost internodes and sheaths of the stems may be swollen and stored with food-materials, and a sort of _tuber_ or _bulb_ results; this is especially apt to occur in dry sandy soils. In old lawns, pastures, &c., the roots of _Poa annua_ and others may have nodules on them due to the presence of certain small Nematode worms, _Heterodera_. [Illustration: Fig. 2. _Nardus stricta._ Plant showing tufted habit, and simple spikate inflorescence, with pointed spikelets all turned towards one side (secund) on the rachis (reduced). Note also the bristle-like (setaceous) leaves at length reflexed. Parnell.] [Illustration: Fig. 3. _Alopecurus geniculatus_, var. _bulbosus_. Plant (reduced) showing habit, bulbous shoots and cylindrical spike-like inflorescences (Foxtail type). Notice the inflated sheaths, and the “kneed” lower parts of the ascending stems. Parnell.] Grasses are annual, biennial, or perennial, and it is often of importance to know which. The point may usually be determined by examining the shoots. If all the shoots have flowering stems in them, and are evidently of the current year, the grass is an annual; but if any shoots have leaves only, it is either biennial or perennial: to determine which is not always easy, but in perennial grasses there will generally be evident remains of older leaf-bases and shoots, and if there are distinct underground stolons or creeping rhizomes as well the point may be considered decided, and the grass is perennial, as is the case with most of our important species. If all the shoots are barren, the grass is a biennial in its first year of growth: if all have flowering stems in them, but show traces of old leaf-bases of the previous year, then the grass is a biennial in its second year. The proof of biennial character is not always easy, however, and a few grasses may be either annual or biennial, or biennial or perennial, according to conditions--e.g. species of _Hordeum_, _Bromus_, &c. In the following lists I have given the duration of the principal grasses, where the character is especially important. ANNUALS. _Phleum arenarium._ _Aira præcox._ _A. caryophyllea._ _Hordeum murinum._ _H. maritimum._ _Lolium temulentum._ _Festuca Myurus._ _Briza minor._ _Poa rigida._ _P. annua._ ANNUALS