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Aethionema retsina

Overview

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Critically Endangered
Threat status

Description

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Family Brassicaceae

Herbs annual , biennial, or perennial , sometimes subshrubs or shrubs , with a pungent , watery juice. Eglandular trichomes unicellular, simple , stalked or sessile, 2- to many forked , stellate , dendritic , or malpighiaceous (medifixed , bifid, appressed ), rarely peltate and scalelike; glandular trichomes multicellular, with uniseriate or multiseriate stalk . Stems erect , ascending , or prostrate , sometimes absent. Leaves exstipulate , simple, entire or variously pinnately dissected , rarely trifoliolate or pinnately, palmately, or bipinnately compound ; basal leaf rosette present or absent; cauline leaves almost always alternate, rarely opposite or whorled , petiolate or sessile, sometimes absent. Inflorescence bracteate or ebracteate racemes , corymbs, or panicles, sometimes flowers solitary on long pedicels originating from axils of rosette leaves . Flowers hypogynous, mostly actinomorphic . Sepals 4, in 2 decussate pairs, free or rarely united , not saccate or lateral (inner) pair saccate. Petals 4, alternate with sepals, arranged in the form of a cross (cruciform ; hence the earlier family name Cruciferae), rarely rudimentary or absent. Stamens 6, in 2 whorls, tetradynamous (lateral (outer) pair shorter than median (inner) 2 pairs), rarely equal or in 3 pairs of unequal length , sometimes stamens 2 or 4, very rarely 8-24; filaments slender, winged , or appendaged, median pairs free or rarely united; anthers dithecal , dehiscing by longitudinal slits. Pollen grains 3-colpate, trinucleate . Nectar glands receptacular , highly diversified in number, shape , size, and disposition around base of filaments, always present opposite bases of lateral filaments, median glands present or absent. Pistil 2-carpelled; ovary superior, sessile or borne on a distinct gynophore , mostly 2-locular and with a false septum connecting 2 placentae; placentation parietal , rarely apical; ovules anatropous or campylotropous, bitegmic, 1 to many per locule. Fruit typically a 2-valved capsule, generally termed silique (siliqua) when length 3 × or more than width , or silicle (silicula) when length less than 3 × width, dehiscent or indehiscent, sometimes schizocarpic, nutletlike, lomentaceous , or samaroid , segmented or not, terete , angled , or flattened parallel to septum (latiseptate ) or at a right angle to septum (angustiseptate) ; valves 2(or 3-6) ; replum (persistent placenta) rounded , rarely flattened or winged; septum complete, perforated, reduced to a rim , or lacking; style 1, distinct, obsolete , or absent; stigma capitate or conical , entire or 2-lobed, sometimes lobes decurrent and free or connate . Seeds without endosperm, uniseriately or biseriately arranged in each locule, aseriate when 1, winged or wingless, mucilaginous or not when wetted; cotyledons incumbent (embryo notorrhizal: radicle lying along back of 1 cotyledon), accumbent (embryo pleurorrhizal: radicle applied to margins of both cotyledons), or conduplicate (embryo orthoplocal: cotyledons folded longitudinally around radicle), rarely spirally coiled (embryo spirolobal) . Germination epigeal.

About 330 genera and 3500 species: all continents except Antarctica, mainly in temperate areas, with highest diversity in Irano-Turanian, Mediterranean, and W North American regions; 102 genera (eight endemic) and 412 species (115 endemic) in China.

Because of lack of a comprehensive classification based on phylogenetic relationships among genera, and in order to facilitate direct comparison between the accounts in FOC and FRPS, the sequence of genera follows Schulz (Nat. Pflanzenfam. 17b: 227-658. 1936) . However, it should be emphasized that his system is largely artificial because he placed closely related genera in different tribes and remotely related genera in the same tribe. For example, Arabis, Aubrieta, Draba, and Macropodium, which are very closely related on the basis of recent molecular studies, were placed by Schulz in four different tribes, whereas the unrelated Capsella, Lepidium, and Thlaspi were placed in one tribe. The delimitation of genera is often difficult, and mature fruits are needed for reliable identification.

The Brassicaceae include many important crop plants that are grown as vegetables (Brassica, Nasturtium, Raphanus) and sources of vegetable oils (Brassica) and condiments (Armoracia, Brassica, Eutrema, Sinapis) . Oils of Brassica probably rank first in terms of tonnage of the world's production of edible oils. The family includes many ornamentals in the genera Erysimum, Iberis Linnaeus, Lobularia, Malcolmia, and Matthiola. Of these, only Lobularia maritima has become naturalized in China. The family also includes more than 120 species of weeds . Arabidopsis thaliana, which is naturalized in China, has become the model organism in many fields of experimental biology .

The delimitation of genera in the Brassicaceae is often difficult because of the frequent independent evolution of what appear to be similar character states , the variability of a given character in one genus and its fixture in another, and the inadequate sampling of material by most authors . Fruit characters are essential in the identification of genera. However, a key emphasizing flowering material is given in addition to the one emphasizing fruit. The most reliable determination of genera can be achieved when the material has both fruit and flowers and when both keys are successfully used to reach the same genus.

The types of cotyledonary position, which in reality is the position of the radicle in relation to the cotyledons (e.g. , radicle accumbent, incumbent, or conduplicate, though radicle referred to as "cotyledon" throughout) are important in the separation of many genera, and a cross section of the seed provides the easiest and simplest way of determining that position. The exact number of ovules per ovary can easily be determined from the fruit because aborted ovules persist through fruit dehiscence. However, it is more laborious to determine the ovule number from pistils and young fruit.[1]

Genus Aethionema

Perennial or annual herbs, often woody below, branched, erect or suberect, leafy, glabrous or rarely papillose . Leaves simple , usually sessile or subsessile , oblong or linear , glaucous. Racemes corymbose , usually many flowered, ebracteate . Flowers mediocre, rose, lilac or white, rarely yellowish; pedicls filiform , usually spreading in fruit. Sepals oblong, obtuse , rounded at apex; inner ±saccate at base ; outer often somewhat hooded at apex. Petals obovate , cuneate or clawed, rarely oblong; claw 1-3-nerved. Stamens 6; filaments of longer stamens append-aged, dilated or linear; anthers often apiculate , ovate-orbicular. Lateral nectar glands in pairs, minute, semiglobose; middle usually absent. Ovary ± ellipsoid with narrowly flattened margin , 1-2-locular with 1-2 (rarely 3-4) ovules in each locule; stigma capitate, sub-sessile or on distinct short style. Siliculae ovate , elliptic or suborbicular , laterally flattened, usually winged , dehiscent , (rarely heterocarpic with dehiscent and indehiscent fruits), 1-4-seeded; apex generally deeply notched or emarginate ; wing entire or variously dentate ; seed ovate, brown, often minutely papillose; radicle incumbent , oblique or accumbent .

About 50 species, chiefly in the Mediterranean region.[2]

Habitat

Ecology: The shrubby perennial is normally found within half a kilometre of the seashore on vertical limestone, 10-200 m above sea level, preferring small crevices and shady habitats .

This species was not discovered until 1969 and officially described in 1973. It is typical of the specialist plant community adapted to grow in the rocky cracks of seashore cliffs . The plant is fleshy , which is an ecological adaptation to salt spray and common in many seashore plants . Scientists have been undertaking crossbreeding experiments with A. retsina and other members of the same family , including plants of enormous agricultural importance such as cabbage, canola and mustard. Scientists are particularly interested in this species' chromosome set and how it relates to that of the cultivated species. One future application could be to genetically improve closely related cultivated species with properties (e.g. , salt tolerance and drought resistance) found in A. retsina.[3]


List of Habitats:3.8Shrubland - Mediterranean-type Shrubby Vegetation 13.1Marine Coastal/Supratidal - Sea Cliffs and Rocky Offshore Islands

Taxonomy

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Notes

Publishing author : Phitos & Snogerup Publication : Bot. Not. 126 (2): 142 (1973).

Similar Species

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Members of the genus Aethionema

ZipcodeZoo has pages for 110 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:

A. acarii · A. alanyae · A. antitaurii · A. apterocarpum · A. arabicum · A. armenum · A. armenum 'Mavis Holmes' · A. banaticum · A. beyrichii · A. bourgaei · A. buxbaumii · A. caespitosum · A. caespitum · A. capitatum · A. cappadocicum · A. cardiophyllum · A. carlsbergii · A. carneum · A. cordatum · A. cordifolium (Lebanon Stonecress) · A. coridifolium · A. creticum · A. cristatum · A. demirizii · A. diastrophis · A. dimorphocarpum · A. dumanii · A. edentulum · A. elongatum · A. eunomioides · A. euonomioides · A. fimbriatum · A. froedinii · A. fruticulosum · A. gileadense · A. glaucescens · A. glaucinum · A. gracile · A. graecum · A. grandiflora · A. grandiflorum (Stonecress) · A. grandiflorum Pulchellum Group · A. heterocarpum · A. heterophyllum · A. huber-morathii · A. iberideum (Persian Candytuft) · A. iberideum 'Rosea' · A. kotschyi · A. lacerum · A. latifolium · A. lepidioides · A. levandowskyi · A. longistylum · A. lycium · A. marashicum · A. marginatum · A. 'Mavis Holmes' · A. membranaceum · A. monosperma · A. monospermum · A. munzurense · A. oppositifolia (Stonecress) · A. oppositifolium · A. orbiculatum · A. ovalifolium · A. pallidiflorum · A. papillosum · A. peregrinum · A. polygaloides · A. pseudarmenum (Stonecress) · A. pulchellum · A. pyrenaica · A. pyrenaicum · A. recurvum · A. retsina · A. rhodopaeum · A. rotundifolium · A. rubescens · A. sagittatum · A. salmasium · A. saxatile · A. saxatile creticum · A. saxatile 'Nana' · A. saxatile subsp. creticum · A. saxatile subsp. oreophilum · A. saxatilis · A. schistosum (Fragrant Persian Stonecress) · A. sintenisii · A. speciosum · A. spicatum · A. spinosum · A. stenopterum · A. stylosum · A. subcapitatum · A. subruticosum · A. subulatum · A. sulphureum · A. syriacum · A. szowitsii · A. szowltzii

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 28, 2007:

Identifiers

Footnotes

  1. Tai-yien Cheo, Lianli Lu, Guang Yang, Ihsan Al-Shehbaz & Vladimir Dorofeev "Brassicaceae". in Flora of China Vol. 8 Page 1. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  2. "Aethionema". in Flora of Pakistan . Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  3. Latroú, G. 2006. In IUCN 2008. 2008 IUCN Red List of Threatened Species. IUCNRedList.org. Downloaded July 19, 2008. [back]
Last Revised: 7/2/2009