Com­mon hog­weed

The Daily Telegraph - Gardening - - Down To Earth -

you dig it out be­fore it seeds it will spread, as it is very much at home in a fer­tile gar­den soil.

Thank­fully it is not poi­sonous to the touch, al­though I do rec­om­mend gloves. It is the roots that are dan­ger­ous, and dig­ging them out is the only ef­fec­tive con­trol. Com­post­ing will not do – this is one for a hot bon­fire.

Iden­ti­fi­ca­tion is not the eas­i­est as there are many mem­bers of this fam­ily ( Api­aceae, which in­cludes cel­ery, car­rots, parsnips, hog­weed etc) that look sim­i­lar. It is an erect clump­form­ing peren­nial with light green fo­liage and flat-topped white flower um­bels that ap­pear in early sum­mer. The fo­liage, as with many in the fam­ily is slightly “cut” or jagged.

Per­haps the most no­tice­able thing of all is the smell of the crushed fo­liage – sickly sweet and pun­gent.

Then there are the roots. They look like a bunch of thick white car­rots and re­mind me of the dead man’s fin­gers in­side crabs that, as chil­dren, we were taught to re­move if a vi­o­lent death was to be avoided. Sur­pris­ingly, the plant is easy to dig up. Stay­ing with the Api­aceae fam­ily,

(Her­a­cleum spho­ndylium) is a na­tive weed that will burn you only, it seems, if you are al­ler­gic to it. My neigh­bor, an avid scyther, was taken by sur­prise when work­ing bare­foot and was blis­tered very badly. How­ever, it is not poi­sonous to eat – in­deed it is beloved of for­agers. Do not con­fuse it with close re­la­tion the ( which is a nat­u­ral-born killer. The sap burns and is deadly if in­gested.

There is no mis­tak­ing giant hog­weed when ma­ture as it is 6ft 6in (2m) tall, with huge white flow­ers. The leaves are cut like those of the com­mon hog­weed and hem­lock, rough to the touch but dark green to the com­mon hog­weed’s much lighter green; a sim­i­lar shape but big­ger.

( is an an­nual weed in the same fam­ily as gar­den busy Lizzies. It has pretty pink flow­ers and a sweet smell. And that is where the pleas­ant­ness ends. It is of­ten brack­eted with Ja­panese knotweed be­cause it colonises and takes over, bul­ly­ing other plants out of the way with its strong-arm tac­tics.

How­ever, it is not a deep rooter and comes out eas­ily when dug or pulled. Do this be­fore it flow­ers to pre­vent its spread. At the end of July it is an ex­pe­ri­ence to find your­self in a grove of bal­sam to wit­ness the seed­pods ex­plod­ing and fir­ing their con­tents all around you.

An­other ex­plod­ing seed spreader is the (

Luke Hazel­ton, nurs­ery man­ager at Tre­withen in Corn­wall, names this in­nocu­ous lit­tle an­nual as his weed of night­mares. Com­ing to fruition in late spring, it too is fa­mous for fir­ing out its ripe seeds.

The prob­lem for Luke is that the weed colonises con­tainer­ised plants and once the seed stock is in the pots the weeds keep ger­mi­nat­ing. How­ever, hairy bit­ter­cress is eas­ily hoed off on dry days.

or mare’s tail ( is on a par with Ja­panese knotweed in its ca­pac­ity to root deeply and with­stand chem­i­cal treat­ment. It in­creases by two meth­ods, spores and rhi­zomes. The spores have jump­ing “legs” that are ac­ti­vated by hu­mid­ity, and the rhi­zomes travel as deep as 6ft 6in (2m) un­der­ground. Not bad for a

Be gone: Tom Peth­er­ick shows off the im­pres­sive root sys­tem of wa­ter hem­lock, left; ox­alis, cen­tre; Tom digs out a stem of horse­tail, be­low

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