OUTLINE OF STRUCTURAL BOTANY 7 
seen at the point of union a ring raised more or less above the sur- 
face of the root at that point. 
The part just below the stem is known as the caudex (a Fig. 7). 
UNDERGROUND STEMS (ROOTSTOCKS, CORMS, BULBS, TUBERS ) 
There are certain modifications of the stem which by reason of 
their position, mostly under the soil, the absence of green coloring 
matter and by their appearance, are, by those who have not con- 
sidered their nature sufficiently, regarded as roots. 
Although these forms are technically modified stems and not 
roots, we may consider them in this place as, to some extent, inter- 
mediate forms. 
If we were to draw from the soft soil a stalk of the common 
quack grass we would observe at its foot a white cylindrical exten- 
sion of the size of the stalk and that at intervals there spring fasci- 
cles of roots and also, if we have not broken the cylinder, that it is 
Fic. 8 Tic. 9 Fic. 10 
Fic. 8—Rootstock of Solomon’s Seal, showing the “seals”? from which arise the 
branches or aerial stems and the scars marking the point of growth of last year’s 
aerial stems, 
Fic. 9—Corm of Jack-in-the-Pulpit. 
Fic. 1o—Bulb of Wild Onion. 
terminated, not by the cap which terminates a root, but by a bud, 
in which it resembles a stem. Its course is horizontal beneath the 
soil and it may at intervals send up several stalks. This white 
cylinder is simply a subterranean stem modified by its position for 
the performance of its office. It is technically a rhizome, but in 
familiar language a rootstock. Such rootstocks are found in case 
of the iris, Solomon’s Seal (Fig. 8), wild azalea and a great many 
other plants, 
4 
