No. 33.] 307 
of a peculiar tubercular growth. This sometimes appeared upon 
the branches also, but never far from the tap root. We have fre- 
- quently noticed this tubercular growth upon pea roots at other times, 
though we have very rarely seen it mentioned. Two German writ- 
ers speak of it, one ascribing it to a fungus growth, and the other 
to bacteria. The subject is evidently little understood. 
July 9 we examined the roots of a plant of American Wonder 
pea, of which the stem was six inches tall, with the pods just past 
the marketable stage. The roots extended almost exclusively down- 
ward, the tap root extending toa depth of thirty inches, with no 
branches extending more than four inches from it. It thus appears 
that the pea, like the clover, alfalfa and some other of the Legum- 
inosae, is a deep rooting plant. We should expect, therefore, that 
where the straw is returned to the soil, peas would prove beneficial 
rather than exhaustive. The deeply penetrating roots doubtless 
draw much of their nourishment from a considerable depth, and 
hence would tend to enrich the surface. As the roots extend hori- 
zontally so short a distance, no objection appears for planting the 
rows of garden peas as near together as convenience in gathering 
will permit, provided that in the taller varieties the rows extend 
north and south so that the sun has opportunity to shine between 
them. 
The deep-rooting character of the pea plant may explain the slight 
infiuence that fertilizers seem to have upon it, as we noted in de- 
tailing our experiments upon this vegetable. 
It appears that while the root system of the Dwarf American 
Wonder pea is less extensive than that of the tall British Queen, 
yet the diminution of the extent of the roots in the former is by no 
means in proportion to that of the stem. 
LETTUCE. 
The roots of lettuce also run chiefly downward. July 9, we ex- 
amined the roots of a plant of the Crisp Small Early Frame variety. 
The flower stalk had then commenced to form, being about six inches 
high. The tap root extended downward to the depth of more than 
twenty-five inches. Fibrous roots started out from this just below 
the surface of the ground, sloping downward at an angle of about 
forty-five degrees, but we were unable to trace these more than a foot 
. from the tap root. The greater part of the fibrous roots lay with- 
in eighteen inches of the surface, and six inches on either side of the 
tap root. 
_ We thus see that the roots of the lettuce plant at this stage of 
growth extend downward four times as far as the stem rises upward ; 
although this proportion is doubtless very much changed after the 
flower stalk is fully formed. It appears also, that for the full de- 
velopmont of the roots, the rows of lettuce should not be less than 
two feet apart. It is evident that where the plants are crowded in 
the bed, as we sometimes see lettuce grown, the root system must 
be correspondiugly dwarfed. 
