Evening star., 1928-03-04

DsELrlct Oh IOlUIlUih anu I1SsAiDs
States are seriously alarmed o;cf
~ an insidious invasion OF the his
toric waters OF the Potomac.
The obstreperous foreigner response
bic for oil the commotion. is q dainty
green water plant, known In Its native
fiaunts Of southern Europe and north
Africa az the water chestnut. that has
pushed the scene OF It's depredati0ns
almost TO the shadow OF the National
Capital. Like the cactus In Australia
and the water hyacinth IN the South. IL
wIs welcomed first as an ornament. but
is r. pidfy arousing resentment az Sc.
riOus enemy.
The alarming spread Of the water
ch@Etnut and the menace It presents To
the game fish and navigation OF the Po-
.omac have been pointed out by Earl
v. Shannon, @ geoioglst OF the National
Museum Mr.. Shannon Is an amateur
naturalist whose training In careful OBJ
seryations In geological field work has
been instrumental! in his foreseeing the
danger OF the pests spread In the cstu-
aries OF the Potomac.
In 1919. Trapa Natans. al this over
friendly ornament Is known TO botan+
ists. was practically extinct after i1 In
PRODUCTION In this neigtborh0od some
wears before. Whatever adverse condi-
tions may have prevailed ut that time.
its spread In the last nine years has
been phenomenal. Small colonies are
located in Swan Creek and Gunsfon
CoYc, and there are undoubtedly many
more that have not been reported. The
Isrges, is in Oxon Creek. just across thf
riyey from Alexandria In 1923 It COW
cred two acres with A dense patch OF
vegetation. with many small scattered
plants surrounding IT.. In 1925. in Au-
rust The season Of maximum growth.
this had grown 10 nfarly 90 acres, In
the FaI of 1927. at the time when the
plants begin 10 disintegrate for the
Winter, the main patch was estimated
AT around 40 acres This gives some
indication If the plants tremendous
rate q! increase IN this climate, where
~ natural enemies are few. " any.
in It's own home In southern Europe.
whore the seeds are roasted and sold on
the street ike chestnutE IL has never
reached peatl!entiai proportions THESE
! @harp. tour horned seeds are The SoiIfce
of the generic name TTapa which In an
authorization ~ "caicitrap" or "cal"
trops" The caltrops sn ancient instrii~
msnt OF war that consisted Of sn iron
ball aith four sharp points 80 arranged
! that when three rested OIL the ground
one still protected In the air. These
1ere scattered over the ground t0 I'M
ilfcr cavalry charges. The seed Is well
nsmGn, ~ many barefoot batip'r
along infested psrts of the Potomac VIII
! testify.
/ When one of TIE ripened seeds dtoDs
fran the attractive rnsstt of leaves
, that constitute The parent niani. Il falls
/ .0 tie EyttDnl, Later d slight ferIaeiita~
! lion takes ptacA that gives IL enough
! iuoVanfv ~ make H. ftGat With the ruf~
| rent until the gas sli reiensrd, II sinks
/ ~ ~" bottom agstn. There II stays unS
! I'll The following Spring. II then sprouts
I and sends np long, fieyibie stem :" tbs
surface The empty seed shell. with hs
! horny coat drops off and washes ashore.
| where II Joins msny others 10 form z
! formidable carpet That INSPIRES ell
/ jiahtlY~ehod investigators with sympa-
| ny for tliF Roman cavalry
The outerm0st leaves of tbs rosette
are provided with air bladders that keep
! iiie plant sfiJaL on an even keel A. all
! times and lldes, II IL = beautiful aud
prolific annual that blossoms and pro
| dlIees fruit continuously oil Summer
| The stAm divides below the surface to
| fofm as many 81 eight fDkEtt&s from n
| single seed Eighteen mature fruits
have besn f1tiHted on one foseitk E,Hce
large proportion III ibs seeds gsimf"
nate successfully single plant is easily