178 
The Ohio Naturalist. 
[Vol. VII, No. 8, 
OHIO PLANTS WITH PUNCTATE GLANDS AND GLANDULAR 
SCALES AND PUBESCENCE. 
Edna M. McCleery. 
The subject of glands is interesting from a morphological as 
well as from a physiological stand-point. In their morphology 
plant glands represent very diverse structures and in the follow¬ 
ing article an attempt has been made to classify certain types 
of Ohio glandular plants as a basis for future ecological and phy¬ 
siological studies. In this paper resin ducts as are present in the 
stems and leaves of Conifers will not be considered. 
There are about sixty Ohio plants which have internal punc¬ 
tate glands such as are found typically developed in the Poly¬ 
gonums and Hypericums. These glands can usually be seen 
with the naked eye if the leaf is held up to the light, but with the 
aid of a small lens all are quite distinctly seen. The glands 
usually appear light in color, but some are black and a few yellow. 
The size is variable but usually the smaller the glands the more 
numerous they are. 
Most punctate glands are internal although some leaves, as 
the prickly ash, have the epidermis modified into large cells 
which are probably used in secreting the contents of the gland. 
The gland of the prickly ash (Fig. 1) is made up of many layers 
of modified cells, each cell having a prominent nucleus. The cell 
and nucleus stain about the same color as the palisade tissue. In 
most of the cross-sections of the leaves the glands are about as 
deep as the palisade tissue, but in some of the older leaves, 
where development is complete the glands extend far down into 
the spongy tissue (Fig. 2). At the top of each gland of prickly 
ash there are a number of cells entirely different from the ordi¬ 
nary epidermal cells. They are larger than the epidermal cells, 
stain about as dark as the palisade tissue and have large dark 
nuclei. They are very conspicuous in a cross-section showing 
as a row of from three to six cells across the top of the gland, but 
in a tangential section they appear in a more or less circular 
plate of from nine to thirty-six cells. 
The internal glands of the Hypericum (Fig. 5) are of much the 
same type, but differ in two particulars. Instead of having a 
many-layered gland-wall, the wall is thin, being made up of a 
single layer of cells. These cells stain darker than any other 
part of the leaf. The cell usually extends about as deep as the 
palisade tissue, although most of the sections of Hypericum show 
a double row of palisade. The second point of difference be¬ 
tween this and the prickly ash is that the Hypericum does not 
have the compact plate of cells in the epidermis. The covering 
above the gland appears perfectly normal. Hypericum macula- 
turn has black dots instead of the light ones. These black dots 
