Short Description
The common hemp-nettlel can grow up to 60 cm high.
The leaves are ovate and toothed at the edge. They grow on the stem opposite each other.
The stem grows erect and is square. It is strongly thickened under the leaves and bristly hairy.
The flowers can have very different colors: white, pink to bluish. The flower consists of five fused petals, which form a typical lip flower. The lower lip has two hollow lobes. The sepals have five very long spiky lobes.
The fruits are small, single-seeded nutlets. They always sit in fours in the calyx of the flower.
Features
Common hemp-nettle
Galeopsis tetrahit
strongly thickened stem at the nodes
two hollow teeth on the lower lip
spiky calyx lobes
Similar species
Bifid hemp-nettle
Galeopsis bifida
Galeopsis pubescens
In the city
Nutrient-rich soils are relatively common in the city. It tolerates them well, so it often grows on fallow land and roadsides. However, it can also be found in fields and clearings. It prefers nutrient-rich and especially nitrogen-rich soils.
Fun Facts
The two hollow lobes on the lower lip serve as guardrails for visiting insects. They have to stick their head between the lobes into the flower to reach the nectar. In doing so, they pollinate the flower.
Larger animals get caught with their fur on the spiny calyx lobes and thus bend the elastic stem. The stem then recoils and ejects the fruits from the calyxes.
Several tit species collect the fruits and build up deposits in the bark of trees.
The flowering period is from June to October.
It is an annual plant. This means the plant dies in the first year after the maturation of the seeds.
- Endangerment level Germany: not endangered
Sources
Habitus, Ivar Leidus, CC BY-SA 3.0, https://commons.wikimedia.org/wiki/File:Galeopsis_tetrahit_-_kare_k%C3%B5rvik_Keilas.jpg
Blüte, Rasbak, CC BY-SA 3.0, https://commons.wikimedia.org/wiki/File:Galeopsis_tetrahit,_gewone_hennepnetel_(5).jpg
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Habitus, TeunSpaans, CC BY-SA 3.0, https://commons.wikimedia.org/wiki/File:Galeopsis_tetrahit_plant1.jpg
Kammer, P. M. (2016) Pflanzen einfach bestimmen. Schritt für Schritt einheimische Arten kennenlernen, Bern: Haupt Verlag.
Spohn, M., Golte-Bechtle, M. & Spohn, R. (2015) Was blüht denn da? Stuttgart: Franckh Kosmos Verlag.
Page „Gemeiner Hohlzahn“. : Wikipedia, The Free Encyclopedia. Date of last revision: 06.01.2018, 17:00 UTC. URL: https://de.wikipedia.org/w/index.php?title=Gemeiner_Hohlzahn&oldid=172655432 (Accessed: 13.02.2018).