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9.34 Thorns aka Puncture Vine


This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.

9.34 Thorns aka Puncture Vine

From: Jobst Brandt <jobst.brandt@stanfordalumni.org>
Date: Thu, 21 Sep 2000 16:54:00 PDT

Those who suffer from thorns should become familiar with the plant
before spending much effort selecting tires that will survive thorns.
Recognition is a large step toward avoiding flats. The plant is not
mobile and does not propel its seed pods away from its tendrils.
However, some riders think nothing of pulling thorns from their tires
and throwing them on the road for other bicyclists to encounter. This
practice seems to be part of not understanding avoidance. In my
experience, riders who suffer most from thorns, have no idea of the
plants appearance or its habitat. Most, think the yellow star thistle
is puncture vine. It is not and is also incapable of causing a flat.

Puncture vine, known as tribulus terrestris, grows mainly on barren
soil, typically on roadsides that have been sprayed with herbicides to
prevent cigarette initiated grass fires. It germinates in early
summer after the first hot days, and grows, radiating with flesh
colored tendrils, from a central root to a radius of about 30 to 50cm,
having 1 x 3 cm filigree dark green leaves that follow the sun. It
has five petal yellow blossoms 1 cm in diameter that produce seed
clusters of five tetrahedral pods with a heavy base and two 3 mm
thorns, one of which preferably points upward when breaking from the
clusters that the plant produces throughout its annual growth.

Some examples:




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