Donnerstag, 22. August 2013

Plant of the Day (August 22nd, 2013) - Listera ovata (L.) R. Br. (also: Neottia ovata (L.) Bluff. & Fingerh.)

In today's portrait, I want to show you Listera ovata (L.) R. Br.; an orchid from the Orchidaceae family (sub-species: Orchideoideae). The Orchidaceae are a form-rich family within the Asperagaless; an order of the monocotyledons. The common German name of this orchid is “Großes Zweiblatt”, while the common English name is “Common Twayblade”.

L. ovata - habitus

Please note: recent, phylogenetic researches have found out a close relation between this species and Neottia nidus-avis (L.) Rich. (“Bird's nest orchid”). As a result, the species is also known as Neottia ovata in newer literature. However, I will use the old name, because it's still more common in books.

1) Description

L. ovata is a perennial plant, which can reach an average height between 20 and 70 centimeters (7.9 to 27.5 inches). It has a short, barrel-like rhizome and flat, creeping roots. The stalk is covered with a loose fluff. The plant also lives in a symbiosis with a fungus, which grows around the roots. This form of symbiosis (Ecto-Mycorrhiza) is very common at the orchids.

L. ovata - the two, egg-shaped leaves

The plant is nearly leafless and has only two large, dark-green leaves at its base, which are egg-shaped. They are arranged in a nearly decussate leaf-pattern. As with the most monocotyledons, the leaf-veins are running parallel to each other. The two-leaves are also responsible for the German name “Zweiblatt”, what means “two-leafed (herb)”). In some cases, there are also some dark spots on the leaves.

L. ovata - flowers

The inflorescence is a single raceme with 20 to 40 flowers. Unlike tropical orchids, the flowers aren't very spectacular. They are small and have a yellowish-green color. As with the most orchids, the flowers have a very unique morphology and consist of two circles: outer and inner tepals. One of the inner tepals is much longer than the rest and is called labellum (lip). The labellum of L. ovata is deeply divided into two tips.

 L. ovata - flowers

In addition, one of the outer petals is puffed-up and form a helm like structure, which closes the flower a little bit. As a result, a potential pollinator (mostly scorpion wasps and beetles), must land on the labellum and crawl into the flower. Now, L. ovata can attach a small package of pollen at the back of the insect.

 L. ovata -  leaves & stalk

The ripe fruits are small capsules with many seeds per capsule. Flowering time is between May and June. However, vegetative reproduction is also possible.

2) Distribution

L. ovata is native to Europe but can also be found in some regions of North America as Neophyte. It grows in deciduous forests, riparian forests, bogs and on meadows. It prefers fresh, shady places on lime or loam, which are rich of nutrients.

young, deciduous forests on lime, like this one in Grube Haan,
are a typical habitats of L. ovata

Like all orchids, the species is strictly protected by the “Convention on International Trade in Endangered Species of Wild Fauna and Flora“ (CITES). So, the destruction and poaching of this plant is forbidden.

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