(air-in' gee-um)

Common name: Sea Holly

Family: Apiaceae, Carrot

Height x width: 1½-2' x 1½-2'

Growth rate, habit: moderate; upright

Foliage: alternate, upper leaves clasping or sessile, lower basal leaves obovate to ovate, variable with species; spiny (spinose), deeply toothed or dissected, often white veined

Flowers: summer, blue heads ½-¾" long and surrounded by 9-15 long, lanceolate involucral bracts making an unusual teasel-like collar around the central flower

Hardiness: zones 3 or 5 -8

Soil: well-drained, prefers sandy and dry

Light: sun

Pests and problems: smut, leaf spots, stem rot (none common or serious)

Landscape habit, uses: foliage or flowers as specimen or emphasis plant, bold texture, dried flowers

Other interest: native to Europe and the Mediterranean; from the Greek word for thistle from its flower resemblance

Other culture: relatively care-free, good for difficult situations-- deserving of wider use; resents moving due to long taproot; if terminal stem is cut flowering side stems often develop

Propagation: root cuttings, division is difficult due to long taproot, seed (10,000 seeds per ounce) although cultivars don't come true reliably from seed, seeds require a warm moist stratification for one month followed by one month of cold moist stratification


Of the 200 or so species, found mainly in the Mediterranean regions, the following are most commonly seen as ornamentals.

alpinum (al-pie' num)--Alpine Sea Holly, 1-3', heart-shaped basal leaves, zones 4-7, native to Europe, one of bluest of genus both flowers and stem

amethystinum (a-meth-stee' num)--Amethyst Sea Holly, 1-1½', pinnately divided basal leaves, zones 2-8, native to Europe, most cold hardy of genus, metallic blue flowers and stems branched near top

bourgatii (boor-gatt' ee-ii)--Mediterranean Sea Holly, 1-2', palmate 3-5 divided basal leaves, zone 5-7, native to Pyrenees, blue-green flowers with many silver bracts, white veins in coarse spiny leaves

giganteum (gii-gan' tee-um)-- Miss Wilmott's Ghost, 4-6', heart-shaped basal leaves, zones 4-7, native to Caucasus, needs staking, large flowers to 4" long with silver bracts; named for famous English gardener Ellen Wilmot in early 1900's who liked this plant and would scatter seeds in other people's gardens if they didn't have it

x oliverianum (ah-liv-er-ee-aa' num)--hybrid possibly between alpinum and giganteum, 2-3', lower leaves ovate with slight lobes, purple bracts and vivid blue flowers, zones 5-7

planum (plaa' num)--Flat Sea Holly, 2-3', heart-shaped basal leaves, zones 5-8, native to Eastern Europe, many silver-blue flower heads ½" long and oval, popular European commercial cut flower, less ornamental than other species for gardens

x tripartitum (tri-par-tii' tum)--hybrid probably native to the Mediterranean, 3', zones 5-7, 3-lobed basal leaves, metallic blue flowers with blue-green bracts

varifolium (var-i-fol' ee-um)--Moroccan Sea Holly, 1-2', rounded basal leaves, zones 5-8, seldom seen species with attractive white-veined leaves appearing variegated, also unusual in being evergreen, useful small habit

yuccifolium (yuk-ki-fol' ee-um)--Rattlesnake Master, 2-4', strap-like basal leaves, zones 5-9, native to the eastern U.S., creamy chartreuse flowers like buttons and not very showy, narrow parallel-veined foliage like yuccas which is main feature of this species; name from myth that plants could cure rattlesnake bites or drive snakes away

x zabelii (zah-bell' ee-ii)--Zabel Sea Holly, 1½-2', cross between alpinum and bourgatii, flower heads 1-2" long with 10-12 long rigid bracts, very showy

Cultivars species height flowers, bracts other
'Amethyst' alpinum 2-3' metallic light blue serrated foliage
'Blaukappe' planum 2' deep blue grows from seed
'Blauerzwert' planum 1½-2' deep blue  
'Blue Cap':'Blaukappe'        
'Blue Diamond' planum 1½-2' deep blue  
'Blue Dwarf':'Blauerzwerg'        
'Blue Ribbon' planum 2' blue appearing double  
'Blue Star' alpinum 2-3' lavender-blue grows from seed
'Donard Blue' x zabelii 2' lavender-blue, large  
'Jewel' x zabelii 2' light blue  
'Opal' alpinum 2' silvery-blue  
'Oxford Blue' bourgatii 2' silvery-blue good color for species
'Silverstone' planum 3-4' creamy white  
'Slieve Donart' alpinum 2' light bracts, dark blue  named for Irish nursery
'Spring Hills' x zabelii 2' lavender bracts, long  
'Superbum' alpinum 2-3' dark blue, large grows from seed
'Violetta' x zabelii 2' dark blue  

©Authored by Dr. Leonard Perry, Professor, University of Vermont as part of PSS123 course.

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