Helwingia
Helwingia japonica
Helwingia is the only genus of the family of Helwingiaceae. Your area extends from the Himalayas to eastern Asia. All species are shrubs. Exceptional are lying on the leaves inflorescences. The genus name honors the East Prussian pastor and botanist Georg Andreas Helwing ( 1666-1748 ).
Features
The species of the genus are evergreen or deciduous shrubs or small trees. They are usually one to two feet tall, rarely up to eight meters. The plants are bare. The leaves are simple, alternate, stalked and have two early falling stipules. The stipules are small and fringed. The leaf margin is glandular, cut or notched. The leaf veins are branched fiederförmig. The stomata are mainly on the lower leaf surface ( abaxial ). In mesophyll no calcium oxalate crystals are present. The minor leaf veins ( small veins ) have no phloem transfer cells.
The flowers are sitting on the midrib of the leaves. The inflorescence is formed in the axil of its liner sheet. This coalescence begins with the leaf or inflorescence - primordia. Through the work of a basal intercalary meristem of the inflorescence comes to sit on the midrib. The inflorescence is supplied by an additional adaxial sitting vascular bundle, which originates at the base of the petiole. It is not clear whether this phenomenon can be interpreted as a simple intergrowth of inflorescence stalk and leaf, or whether a different ontogenetic explanation must come to fruition.
The plants are dioecious ( dioecious ). The inflorescence is a Zyme. There are three to four (five) calyx teeth. The also three to four (five) petals are green to purplish - green. The male flowers are about three to 20 in an inflorescence and have three to four (rarely five) stamens in a circle, which are alternating with the petals. The anthers open by longitudinal slits. The pollen is tri - aperturat and colporat. The female flowers are only up to fourth in the inflorescence. The stylus is short. The ovary is inferior and consists of two to four carpels. Per carpel there is an incomplete tenuinucellate ovule. The scar with three to four (rarely five) stigma lobes is dry.
The fruit is a drupe -like berry with a few nuts / seeds. The fruit is round, immature green and mature red to black. The seed coat ( testa) is thin. The endosperm is easy ruminiert, i.e. fold like tissue growths from the nucellus of the endosperm is furrowed.
At phytochemicals flavones, chlorogenic acid and unidentified iridoids are present. The chromosome number is n = 19
Dissemination
The area stretches from the Himalayas to eastern Asia. The genus is found in Bhutan, China, northern India, Japan, South Korea, North Myanmar, Nepal, Sikkim, Thailand and North Vietnam.
System
The Helwingiaceae are within the order Aquifoliales the sister group of the Aquifoliaceae. The common features are: arc-shaped vascular bundles in the petiole spirally standing leaves.
The genus was first described by Carl Ludwig Willdenow 1806: Sp Pl 4: 716 (1806 ).
There are four types:
- Helwingia chinensis Batalin, Trudy Imp S. Peterburgsk. Sada Bot 13: 97 ( 1893).
- Helwingia himalaica Hook.f. & Thomson ex C.B.Clarke in J.D.Hooker, Fl. Brit. India 2: 726 ( 1879).
- Helwingia japonica ( Thunb. ) F.Dietr. , Supplem completeness. Lex Gaertn. 3: 660 (1817 ).
- Helwingia omeiensis ( W.P.Fang ) H.Hara & S.Kuros. in H.Hara, Fl. E. Himal. , 3rd. Rep.: 410 ( 1975).
Helwingia argyi H. Léveillé & Vaniot is not a valid synonym for Stemona japonica (Blume ) Miquel, a Stemonaceae.
In the scheme of angiosperms after Schmeil - Fitschen it is not considered as a separate family, but referred to as belonging to the dogwood plants.