IOWA ACADEMY OF SCIENCE 
35 
above organizes the dermatogen. Just back of the meristem appears the pro- 
toxylem which for some time is entirely separated from the vascular tissue of 
the root; the tissues of the cortex remain undisturbed for some time. How- 
ever, the oldest buds which we have sectioned show signs of the vascular 
region of the stem extending down to the one in the root. 
Convolvulus sepium L. Common Morning Glory. 
Roots. The small whitish roots usually spring in pairs from the base of 
the scales. The roots like the rhizomes are extremely fragile. The number 
and character of the secondary roots differ in different plants. 
Stem. The plant propagates freely by its underground stem. The rhizomes 
are fleshy, dirty white in color, and very fragile. They extend horizontal, verti- 
cal, oblique, ascending, or descending from a few inches to two or three feet into 
the ground. The nodes occur at short intervals. The small roots usually occur 
in pairs, a point noted by Hitchcock and Clothier. One or more aerial stems 
spring from the upper nodes. 
The anatomy of the stem has been studied by Gerard^® and Costantin®^ the 
latter giving a careful description of the anatomical structure. The root stock 
is essentially a storage reservoir for food, every part but the vascular tissues 
being fllled with starch, a comparatively small part being occupied by the vas- 
cular elements. The epidermis consists of somewhat elongated thin walled 
epidermal cells, underneath which are small hypodermal cells, and small inter- 
cellular spaces. The cells vary somewhat in size. The inner layer of the 
parenchyma cells forms the endodermis. The vascular elements form a ring 
connected by the cambium. There are four large bundles with a few inter- 
vening very small bundles. The bundles belong to the bicollateral type with 
sieve elements and cambial layers between the endodermis and pith paren- 
chyma. The sieve elements towards the pith form irregular areas. The xylem 
elements consist of scalariform ducts. The pith parenchyma is sharply differ- 
entiated from the cambium. 
Convolvulus arvensis L. Bindweed. 
Roots. Convolvulus arvensis propagates by means of small creeping horizon- 
tal roots. The younger ones are whitish, becoming much darker in color with 
age. Small branches appear at irregular intervals. 
The anatomical structure consists of the following parts, an epidermial layer 
of rather large cells, a deeply staining hypodermal layer, followed by two 
layers of cells somewhat longer than wide. The remaining eells of the cortex 
are large, gradually becoming smaller toward the vascular region. The cells 
contain a small amount of protein, iSie starch grains having disappeared at the 
time of examination in the spring. Some of the cells contain crystals of cal- 
cium oxalate. A conspicuous nucleus and nucleolus is present in most of the 
cells. 
The xylem consists of large ducts and thick walled cells, arranged radially 
with the phloem. The medullary rays extend from the cambium in toward the 
center of the root which consists of five rays projecting into the xylem. 
The root produces adventitious buds. These give rise to short vertical 
stems which often give rise to other new stems. 
361. C. 
c.. 
