Hedge Bindweed can be­come trou­ble­some

Wicklow People (West Edition) - - LIFESTYLE - JIM HUR­LEY’S

HEDGE Bindweed put on a great show this year with lots of hedgerows sport­ing the plant’s large, white, trum­pet-shaped flow­ers. While at­trac­tive in the wild, it is an un­wel­come species in gar­dens as it can be­come a trou­ble­some weed.

How­ever, sus­tained pulling out of the strag­gly shoots soon weak­ens the root and the in­vader can be eas­ily erad­i­cated with per­sis­tent ef­fort over a num­ber of years.

Com­pared to the large flow­ers, the stems are strag­gly, skinny and wiry. They are so skinny they can­not sup­port the plant, so they cling to any struc­ture to hand. They twine around the branches and twigs of a gar­den hedge al­ways grow­ing up­wards but do­ing so spi­rally in an an­ti­clock­wise direction. But how can they al­ways grow in an an­ti­clock­wise spi­ral?

Plants have hor­mones in the same way that we have. Plant growth hor­mones are a small fam­ily of chem­i­cals called aux­ins. Aux­ins are found in cells in tiny quan­ti­ties. They are more con­cen­trated in the grow­ing tips of plants and it is that in­creased con­cen­tra­tion that causes the tips to grow. More hor­mone means more growth.

Plant shoots al­ways grow up­wards, so it ap­pears that plants ‘know’ up from down. Aux­ins re­spond pos­i­tively to light and neg­a­tively to the pull of grav­ity. The com­bined ef­fect of their pos­i­tive re­sponse to light and their neg­a­tive re­sponse to grav­ity causes aux­ins to mi­grate to the tops of cells thereby con­cen­trat­ing max­i­mum growth there re­sult­ing in the plant grow­ing up­wards to­wards the light and away from the pull of grav­ity.

In ad­di­tion to that, aux­ins are sen­si­tive to touch, not just any touch but in Hedge Bindweeds touch specif­i­cally on the left-hand side. So, if the tip of a shoot grow­ing up­wards in a hedgerow touches a twig on its left-hand side, the cells im­me­di­ately re­spond by dif­fus­ing aux­ins to the right-hand side of the cells and tis­sues.

The re­sult­ing in­creased con­cen­tra­tion causes the right-hand side to grow faster than the left re­sult­ing in the shoot turn­ing to the left. The more the plant touches on the left the more it grows on the right caus­ing the skinny shoot to twine an­ti­clock­wise around the twig while grow­ing up­wards all the time.

In ad­di­tion to aux­ins, other chem­i­cals are in­volved ei­ther by in­creas­ing their con­cen­tra­tion or by block­ing their im­pacts. Ex­actly how Hedge Bindweed man­ages to scram­ble through hedgerows by al­ways twin­ing around sup­ports in an anti-clock­wise direction is still the sub­ject of on­go­ing in­ves­ti­ga­tion.

Hedge Bindweed is a com­mon wild plant found through­out all parts of Ire­land.

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