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Alyssum alyssoides

(Yellow Alyssum)

Common Names

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Click on the language to view common names.

Common Names in English:

Hoary Alyssum, Pale Alyssum, Pale Madwort, Yellow Alyssum

Common Names in Portuguese:

Alisso

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 Alyssum

Herbs annual , biennial, perennial , or rarely subshrubs . Trichomes stellate , stalked or sessile, with 2-6 minute basal branches from which originate up to 30, simple or branched rays , sometimes trichomes lepidote, rarely mixed with simple and forked . Stems erect or decumbent , simple or branched. Basal leaves petiolate or sessile, rosulate or not rosulate, simple, entire. Cauline leaves petiolate or sessile, cuneate or attenuate, not auriculate , entire. Racemes few to many flowered, dense or lax , ebracteate , corymbose or in panicles, elongated or not in fruit. Fruiting pedicels ascending , divaricate , or reflexed . Sepals ovate or oblong , base of lateral pair not saccate . Petals yellow, white, or rarely pink; blade suborbicular , obovate , or spatulate , apex obtuse or emarginate , glabrous or pubescent outside. Stamens 6, tetradynamous ; filaments wingless or uni- or bilaterally winged , appendaged or not, toothed or toothless; anthers ovate or oblong, apiculate or not at apex. Nectar glands 4, lateral, 1 on each side of lateral stamen; median glands absent. Ovules 1 or 2(or 4-8) per ovary; placentation apical or parietal . Fruit dehiscent silicles , oblong, ovate, obovate, elliptic , obcordate , or rarely globose , strongly latiseptate or rarely inflated , sessile; valves veinless, pubescent or glabrous, smooth ; replum rounded ; septum complete , membranous, translucent , veinless; style distinct ; stigma capitate, entire. Seeds biseriate , winged or wingless, orbicular or ovate, flattened; seed coat smooth or minutely reticulate , mucilaginous or not when wetted; cotyledons accumbent or incumbent .

About 170 species: primarily in SW Asia and SE Europe; ten species in China.

In his protologue of Ptilotrichum, Meyer (in Ledebour, Fl. Altaic. 3: 64. 1831) distinguished the genus by having white flowers, edentate filaments, and 1-seeded locules. However, these characters are also found in Alyssum, in many species of which one of the two ovules fails to mature into a seed, while in others the filaments are edentate. As for the flower color, it is definitely unreliable in Alyssum sensu lato, just as is the case in numerous other genera of the family , namely Cardamine, Draba, Lepidium, and Rorippa. In fact, the filament base in most plants of P. canescens, the generic type of Ptilotrichum, produces a small, basal tooth. If one accepts Ptilotrichum as a distinct genus, then at least five of the other segregates of Alyssum (Gamosepalum, Meniocus, Odontarrhena, Psilonema, and Takhtajaniella) should also be recognized, an action that the present authors do not support , especially after examining the genus critically on a worldwide basis.

Although Alyssum fedtschenkoanum N. Busch was suspected in FRPS to occur in W China, the present authors have seen no Chinese material in the numerous herbaria they consulted both inside and outside of China. The species is narrowly endemic to Kazakhstan. It is likely that the plant recorded in FRPS represents a minor variant of the widespread and highly variable A. tortuosum.

The ovule number and placentation are important in the identification of the species and can be easily observed in the fruit.[2]

Physical Description

Species Alyssum alyssoides

Herbs annual , 5-35(-50) cm tall, canescent with appressed , sessile, 6-10-rayed stellate trichomes , these mixed with simple and forked ones on pedicels and sepals. Stems erect , ascending , or decumbent , 1 to several from the base . Cauline leaves subsessile or lowermost shortly petiolate ; leaf blade narrowly oblanceolate or linear , sometimes spatulate or obovate , 3-4(-4.5) cm × (0.5-) 1-3.5(-5) mm, base attenuate or cuneate, apex obtuse or acute. Fruiting pedicels divaricate or ascending, 2-5(-6) mm, slender, straight, covered with stellate trichomes mixed with fewer, simple and forked ones. Sepals oblong , (1.5-) 2-3 × 0.7-1.1 mm, persistent , pubescent as pedicels. Petals white or pale yellow, linear to linear-oblanceolate, rarely obovate, 2-3(-4) × 0.3-0.7(-1) mm, glabrous or sparsely stellate outside, often persistent, apex emarginate . Filaments 1-1.5 mm, slender, neither appendaged nor toothed ; anthers ovate , 0.15-0.2 mm. Ovules 2 per locule. Fruit orbicular , (2-) 3-4(-5) mm in diam., apex emarginate or truncate ; valves not veined, uniformly inflated at center, strongly flattened at margins , sparsely stellate; style 0.3-0.6(-1) mm, slender, usually glabrous. Seeds 1 or 2 per locule, oblong or ovate, 1.1-2 × 0.7-1.1 mm, compressed , narrowly margined all around, margin ca. 0.1 mm wide. Fl. and fr. May-Jul. 2n = 32. [source]

Habit: Forb/herb

Flowers: Profuse, fragrant flowers on compact plants . Blooms from late spring to early winter, or year-round in frost-free climates. Dense clusters of tiny flowers bloom continuously throughout the growing season if the spent blossoms are trimmed back. Fragrant. Attracts bees, butterflies, hummingbirds.

Size/Age/Growth

Growth Rate: Fast. • Size: 6-12" tall and wider.

Landscaping

Landscape Uses: Borders . Disturbed areas. Rock gardens. Hanging baskets. Low edging for gardens. Containers . Annual groundcover. • Care: Drought tolerant . Heat resistant. Requires very little attention.

Habitat

Roadsides, waste grounds , disturbed sites; near sea level to 2800 m [3].

Typically found at an altitude of 0 to 3,180 meters (0 to 10,433 feet).[4]

Biology

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Reproduction

Duration: Annual , Biennial

Growth

Culture: Space 10" apart. To propagate from seed, allow seedheads to dry on plants before collecting. Sow outdoors in early spring after danger of frost has passed. Seeds germinate in 7 to 14 days at 65 degrees to 70 degrees Fahrenheit . May also be grown from herbaceous stem cuttings.

Soil: Adapts to almost any soil.

Sunlight: Sun Exposure: Sun or part sun. Grows best in full sun in cool weather, but it will tolerate partial shade.

Moisture: Water Requirements: Average water needs. Water regularly, but do not overwater.

Temperature: Cold Hardiness: 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b. (map)

Taxonomy

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Unambiguous Synonyms

  1. A. campestre (Linnaeus) Linnaeus
  2. Adyseton Alyssoides
  3. Adyseton alyssoides (L.) Nieuwl.
  4. Alyssum calycinum L.
  5. Alyssum calycinum Linnaeus
  6. Clypeola alyssoides L.
  7. Clypeola alyssoides Linnaeus, Sp. Pl. 2: 652. 1753
  8. P. calycinum (Linnaeus) C. A. Meyer.
  9. Psilonema alyssoides (Linnaeus) Heideman

Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000

Place of publication : Syst. nat. ed. 10, 2:1130. 1759

Name verified on 19-Dec-1989 by ARS Systematic Botanists. Last updated: 02-Jan-1996

Similar Species

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Members of the genus Alyssum

ZipcodeZoo has pages for 455 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:

A. affine · A. afghanicum · A. airense · A. aizoides · A. akamasicum · A. albescens · A. alpestre · A. alpinum · A. alsinefolium · A. altaicum · A. alussoides · A. alysoides · A. alyssoides (Yellow Alyssum) · A. alyssoides subsp. hispanicum · A. alyssoides var. hispanicum · A. americanum · A. amoris · A. anamense · A. anatolicum · A. andinum · A. antiatlanticum · A. antilibanoticum · A. 'Aphrodite Lemon' · A. arabicum · A. arcticum · A. arduini · A. arenarium · A. argenteum (Argenteum Basket of Gold) · A. argentum · A. argyraeum · A. argyreum · A. argyrophyllum · A. armemum · A. armenum · A. arvaticum · A. atlanticum · A. atlanticus · A. aucheri · A. aurantiacum · A. aureum · A. auriculatum · A. baeticum · A. baicalicum · A. baldaccii · A. balkanicum · A. baumgartnerianum · A. berlandieri · A. bernhardii · A. bertolinii · A. bertolonii · A. betpakdalense · A. beugesiacum · A. bilimekii · A. biovulatum · A. blepharocarpum · A. boliviense · A. bornmuelleri · A. borysthenicum · A. borzaeanum · A. brachystachyum · A. bracteatum · A. brasi · A. brevifolium · A. brigantiacum · A. brughieri · A. bulbotrichum · A. bulgaricum · A. buschianum · A. cadevallianum · A. caespitosum · A. caliacrae · A. calicinum · A. callichroum · A. calycinum · A. calycionides · A. calycocarpum · A. campestre · A. campestre strigosum · A. campestris · A. canescens · A. caricum · A. cassium · A. castellanum · A. cedrorum · A. cephalotes · A. chalcidicum · A. cheiranthifolium · A. chlorocarpum · A. chondrogynum · A. ciliatum · A. cilicicum · A. clastopus · A. clypeatum · A. cochleatum · A. collinum · A. compactum · A. condensatum · A. conglobatum · A. constellatum · A. contemptum

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 16, 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. "Alyssum". in Flora of China Vol. 8 Page 59. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  3. "Alyssum alyssoides". in Flora of China Vol. 8 Page 60. Missouri Botanical Garden Press. Online at EFloras.org. [back]
  4. Mean = 327.340 meters (1,073.950 feet), Standard Deviation = 497.400 based on 1,360 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/1/2009