1890.] The Knees of the Taxodium distichum. 337 
trative sketches before placing it before botanists. Some recent publi- 
cations on the subject by widely and favorably known authors have, 
however, ascribed to the Cypress-knees the sole function of aérating 
the sap of the parent tree, and this idea bids fair to become embedded 
in botanical literature. Therefore this communication comes to you 
earlier than I had purposed sending it. 
Stretches of the shore of Lake Monroe, in central Florida, are closely 
set with large Cypress-trees. They grow in various kinds of bottom, 
—clay, mud and sand. Those of which I shall here speak stood in 
sand so loose that when the level of the water was lowered the waves 
readily washed it away and carried it into the depths of the lake. 
me four vertical feet of the root-system were thus finely exposed. 
After several days spent in examining a score or more large trees that 
had been thus denuded I became convinced that the most important 
function of the Cypress knee is to stiffen and strengthen the root, in 
order that a great tree may anchor itself safely in a yielding material. 
The word ‘‘ anchor ’’ is indeed an apt one here, for the living root, 
curved to its work and firmly grasping the sandy bottom, suggests viv- 
idly the best bower-anchor that a man-of-war may throw into similar 
oose sands, when threatened by the very atmospheric forces that the 
Taxodium has been fitting itself to resist since Tertiary times.4 
Truly a most admirable and economical arrangement to stiffen and 
strengthen the connection between the shank of the anchor and its 
fluke is this knee, and usually in the living anchor the fluke branches 
or broadens as it descends, so that its effectiveness is greatly increased, 
like the sailor’s anchor of many flukes, or the ‘‘ mushroom anchor ”’ 
that he may have learned to depend upon where the bottom is softest. 
The accompanying picture (see page 20) is from a photograph that 
I made in 1887 of the lower portion of a tree that rises some seventy 
feet above the shore line of Lake Monroe. The original surface of the 
sand was near the level of the higher roots. The picture shows the 
manner in which this peculiar species throws out horizontal roots from 
its conical (usually hollow) buttressed base. At different distances 
from this conical base these horizontal roots project strong branches 
more or less perpendicularly into the earth. When such perpendicular 
‘* flukes ’’ branch from the main horizontal ‘“ shank,’’ it will be seen, 
4 My friend Thomas Meehan informs me [December 17th, 1889] that he has “ observed 
a case where the interior hollow makes an annual layer of bark equally with the exter- 
ior,” and he is of the a mat a ai is by the decay of me area enya of this inside 
course of bark after seve this habit is general 
it is an — menne of kebi ae of Po aena a ge smallest cos 
e tree, a f the 


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Am. Nat. aApdls. 
