Coriaria

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Coriaria

Description

Shrubs (rarely perennial herbs with herbaceous stems) or small trees. Leaves generally small, sessile or subsessile, with a narrow joint at base, simple, entire, cordate-ovate to lanceolate, acute, decussate, or (not in Malesia) in whorls, phyllotaxis of the lateral branches mostly showing as pseudo-distichous; Stipules absent (but see note). Flowers in the axils of small bracts, greenish or reddish, actinomorphic, hypogynous, polygamous, i.e., bisexual or functionally unisexual (both male and female flowers with rudiments of the other sex). Stamens 10, in two whorls, free, or those opposite the petals adnate to the keel of the petal; Ovules one per carpel, pendulous, anatropous, with the micropyle directed upwards. Seed compressed, without an aril, testa thin, endosperm scanty or none;

Distribution

Antarctic: Asia-Temperate:, Hainan (Hainanpresent) Asia-Tropical:, Pakistan (Pakistanpresent); Philippines (Philippinespresent) Chile: present E Asia: present Himalayan region: present Japan: present Luzon: present New Zealand: present Northern America: Papua New Guinea: present SE Asia: present Southern America:, Peru (Perupresent) West-Mediterranean: present
About 20 species, depending on the taxonomic treatment (see infra-generic variation), with a much broken distribution: the West-Mediterranean, the Himalayan Region from Pakistan to SE Asia, and E Asia (Japan, China, incl. Hainan), through Malesia (rare) to New Zealand (and the Subantarctic Islands), Chile, Peru as far North as Mexico; in Malesia: the Philippines (Luzon) and Papua New Guinea.

Anatomy

Leaf anatomy. Cuticle striated; stomata paracytic; lamina dor-siventral; midrib with single collateral vascular strand supported by weakly developed sclerenchyma caps.

Wood anatomy. Wood weakly semi-ring-porous or diffuse-porous. Vessels angular, thin-walled, in multiples and small clusters, rarely solitary, with simple perforations and alternate intervessel pits with slit-like, occasionally coalescent apertures. Vascular tracheids, resembling narrow vessel elements, present in association with vessel groups. Ground tissue composed of libriform fibres. Parenchyma vasicentric to confluent, fusiform or in 2(-4)-celled strands. Rays multiseriate, broad and tall, composed predominantly of erect and square cells, integrading with procumbent cells. Crystals present in some ray cells. Vessel elements, axial parenchyma, and sometimes also the fibres storied.

Carlquist (1985) concluded that the affinities of Coriaria remain elusive, despite some wood anatomical similarities with Corynocarpus, woody Ranunculaceae, and several Simaroubaceae. (P. Baas)

Cytology

The basic chromosome number is x = 20; the somatic chromosome number is for the majority of species, including the Malesian representatives, 2n = 40, but outside Malesia tetraploidy (2n = 80) also occurs.

Uses

Rich in tannin, used locally for tanning and black-dye. The flowers and fruits contain a narcotic, poisonous substance, coriariin. Some Coriaria species (e.g. the Mediterranean C. myrtifolia L., some New Zealand species, and also C. papuana) possess root nodules with nitrogen-fixing properties. As these species often grow in pioneering situations, such as lava fields and roadsides, they may have a place in planting programmes for erosion control in wet scree country (Daly et al. 1972). Coriaria nepalensis (India) is one of the food plants of the silk moth.

Notes

In and beside the leaf-axils numerous minute, fleshy, finger-shaped, and glandlike emergentia are usually present. These have been called stipules by various authors.

Phytochemo

The monogeneric family has its name from the Latin corium (= leather) because leaves and twigs of the Mediterranean Coriaria myrtifolia were formerly used in tannery. Chemical characters of Coriariaceae were summarized by Hegnauer (1964, 1989), where many references to phytochemical and toxicological literature are available. The phytochemistry of this small family is surprisingly well known. All species seem to contain bitter, toxic lactones and to produce large amounts of ellagitannins accompanied by lesser amounts of precursor gallotannins.

The toxic, lactonic principles are picrotaxan-type sesquiterpenes. Coriamyrtin, corianin, rutin (from the Maori name 'Tutu' of the genus), and pseudotutin are the toxic picrotoxin-like compounds of Coriaria. All Coriaria species are known to be toxic. The picrotaxans are a group of convulsive, insecticidal and ichthyotoxic natural products which occur erratically in angiosperms (also known from a few genera of Menispermaceae, Euphorbiaceae, Orchidaceae).

The eUagitannins of Coriaria japonica were studied thoroughly by Okuda's group (Okuda et al. 1990,1993). Monomeric ellagitannins like tellimagrandin-I and -II, coriariin-B and -F and geraniin and dimeric ellagitannins like coriariin-A and -C to -E, and rugosin~D and -E are produced by this taxon which also contains trigalloylglucose.

Glycosides of the flavonols kaempferol and quercetin are present in leaves of all species which have been investigated. They are accompanied in most species by the 7-glucoside of the flavanone naringenin.

Fruits, leaves and twigs of the South American species C. ruscifolia yielded the triterpenic acid ursolic acid and phytosterins and coriamyrtin.

The carbohydrate metabolism of the family shows special features. A new heptulose, coriose, was isolated from roots, stems, leaves, fruits and seeds of C. japonica; it is accompanied by sedoheptulose in leaves and by a corresponding heptitol, volemitol, in seeds. Coriose and another heptulose are also present in C. intermedia, nepalensis, ruscifolia and thymifolia. Myo-inositol is also present in easily detectable amounts in all parts of C. japonica.

Seeds contain much fatty oil (up to 70% of kernels) with an unusual fatty acid, coriolic acid, as the main fatty acid. Coriolic acid is 9-cis, 11-trans-13-hydroxyoctadecadienoic acid; this acid can be interpreted as a monohydrated α-elaeostearic acid. Seed oils of all investigated species, C. myrtifolia, nepalensis, papuana, ruscifolia, sarmentosa and terminalis, contained this new fatty acid.

On account of its chemistry the family must belong to the core of dicotyledons which produce and accumulate ellagitannins.

Phytochemistry suggests Euphorbiaceae on the one side and Crassulaceae-Saxifraga-ceae s.str. on the other side as good candidates for remote relatives. Thorne (1992) classifies Coriariaceae in Rutanae in the most recent version of his phylogenetic system of angiosperms and Huber (1991) suggests close relationship with Anacardiaceae. (R. Hegnauer)