Underground runners (Resumé). 



There are in vascular plants several ditFerent types of plagiotropic shoots, which have 

 not, however, been given definite names, so that we find, for instance, the same type referred 

 to by some writers as a stolon, by others as a rhizome. Distinction should at any rate be 

 made between the following. 



1. In many herbaceous species, the orthotropic aerial shoots send out pIagiotro])ic 

 overground root forming shoots (runners) with elongated internodes, and naturally, with 

 foliage-leaves. These runners should be called stolons (a certain type flagellum). Their 

 biological function is to effect the migration of the plant. 



2. Many species with orthotropic aerial shoots have pale, slender underground runners 

 with scale leaves and elongated internodes; they take root, and ramify irregularly. These 

 should be kept distinct from the stolons, and it is suggested that they be called su bo les 

 {planta subolifera). They are probably never produced by direct transformation of the pri- 

 mary shoot, but are shoots of a second and higher order. Their biological function is like- 

 wise to effect the migration of the plant. It is this type more particularly which is dealt 

 with in the present paper. An example is shown in fig. 1, Aspcriila odorato. 



3. In some cases, they terminate in a nutritive organ, which may be a stem-tuber, 

 fleshy root, or bulb; the hibernating buds are connected with this organ, the nourishment 

 of which is used next spring, but the true migratory part of the shoot dies off sooner. Ex- 

 ample, Solaiiiini liibcrosiim, lig. 37; Slachfis Sicholdi, fig. 34; Cypcrus csculentus, fig. 39; etc. 



4. Underground — and consequently pale — plagiotropic shoots, with short internodes, 

 and rich in nutritive matter and therefore thick, — and which often live for several years, 

 are called rhizomes; they form an important central organ of the jilant, and that from 

 which the aerial shoots proceed. These last are in most species developed from the terminal 

 bud of the rhizome (sympodial rhizomes); in a smaller number of species, from the lateral 

 buds i'monopodial rhizomes). The rhizome is oflen formed directly from the primary shoot 

 (example: Anemone nenwrosa, Pohjgonatum muUijlonim). A somewhat divergent form of 

 rhizonte is found in Uentaria hiilbifera, where not only the stem, but also the scale leaves 

 are nutritive (fieshy); see fig. 2. 



5. Between the suboles and the rhizomes we have another type, resembling the former 

 in being slender, with elongated internodes, but more like the rhizome in the fact that its 

 lateral shoots are formed from certain main buds, situate in the axil of a certain leaf, the 

 leaf in question being often numerically definable. These are often but short-lived. Examples: 

 Hipparis vnlijüris, Heleoeharis pahislrh etc. See p. 302. We might i)erhaps call them rhizodes. 



6. We nuiy here further mention two other types of plagiotropic shoots, which arc not 

 lateral shoots on an orthotropic aerial shoot, and which in some forms run above ground, 

 in others below, but in all cases directly i)earing the green foliage-leaves, besides occa- 

 sionally having scaleleaves. The o vergrou nd root-forming ty|)es are thus creeping (rc/jczi/cs) 

 and should perhaps be called creeping plants (creepers), e. g. Lysimachia niimmnlaria, 

 Hydrocotyle vuk/aris. The underground forms have a thinner or thicker stem, from which 



D. K.D. Vidcnsk.Selsk.Skr. natunidensk.ogmalheni. .\td., 8. Række, II. 6. 49 



