Saxifraga 

(sax-i-frag' ah)

Common name: Saxifrage

Family: Saxifragaceae, Saxifrage

Height x width: 3-12" x 3-12"

Growth rate: moderate

Foliage: dense tufts of palmately dissected (x arendsii) or basal rosettes of oblong (paniculata); quite variable although sometimes reniform (kidney-shaped)

Flowers: rose to blood red (x arendsii) or creamy white (paniculata); spring, early summer

Hardiness: varies 2-7 to 7 with species

Soil: well-drained but moist, prefer neutral to slightly alkaline generally

Light: sun in north to part shade where warmer or shade for some species

Pests and Problems: rusts, aphids

Landscape habit, uses:rock gardens, wall gardens, trough gardens

Other interest: name comes from the Latin saxum meaning rock and frango meaning to break, refering to its nature of growing in rock crevices; another interpretation relates to its mention in the 16th century Doctrine of the Signatures as as cure for bladder or kidney stones ("to break stones") due to its kidney-shaped leaves.

Other culture: does not do well in heat and humidity; often very demanding of soil type and moisture, many only for collectors with specific controlled conditions

Propagation: seeds (several years to bloom), spring or summer division, cutting of single rosette

Species:

The 370 annual and perennial species have been divided in sections (and of interest primarily botanically, into subsections). Most references have a slightly different classification system. The one below is based on Gornall (Bot. J. Linn. Soc. 95(4):273-292, 1987) as described in Jelitto and Schatt, 1990 and includes 14 of the 15 sections which contain perennials or biennials.

Section--Latin characteristics

1.Euaizoonia Silver Rosetted, Encrusted; above-ground rhizomes, tough chalky rosettes

2.Porophyllum Early Spring Rockfoil; dense and firm rosettes, evergreen, chalky margins

3.Dactyloides Mossy Saxifrages; soft-leaved rosette, above-ground stolons, dense mat

4.Porphyrion small, leathery evergreen leaves, often prostrate stems

5.Robertsoniana evergreen, above-ground stolons, leathery basal rosettes

6. Diptera hairy with runners, rounded leaves, summer or fall bloom, likes humus soil

7. Nephrophyllum usually biennial, reniform leaves toothed or divided

8. Trachyphyllum evergreen, grass-like cushions, leaves simple

9. Xanthizoon evergreen, mats or cushions, alternate fleshy leaves lime encrusted

10. Cymbalaria biennial or annual, leaves alternate often fleshy and palmately lobed

11. Miscopetalum small and bushy, short above-ground rootstock, reniform toothed leaves

12. Boraphila tall 1-3' tall, thick rootstock, basal leaves, moist woodland acidic site

13. Tridactylites lime-loving, usually biennial, basal palmately lobed leaves, floriferous

14. Hirculus deciduous, clump-forming, basal leaves with petioles, late summer, humus soil
 
 


The following are the more commonly available in commerce in the U.S. Dactyloides section (3) consists of the Arendsii hybrids . Other hybrids among several species are listed in the section most relevant. Zones are for cold hardiness.
 
 
 
Taxa (section) zone flowers other  
aizoides (9) 2-5 yellow, orange cymes low evergreen mat for moist, difficult  
aizoon:paniculata        
x andrewsii (1) 3-6 white 8" high, loose rosettes  
x angelica (2) 6 red, often bright blue to gray-green cushion of rosettes  
x apiculata (2) 6 white or pale yellow floriferous  
'Aureopunctata' (5) 5 white, pink x urbium, golden variegated leaves, sun  
x biasolettii (2) 6 carmine red, especially buds rosette leaves long, acute  
'Blood Carpet' 3 carmine red 4-8" tall, from seed  
'Blutenteppich':'Blood Carpet'        
x boydii (2) 6 light yellow, few in groups sea-green dense mats, small-leaved  
x burnatii (1) 5 white natural hybrid of maritime Alps  
burseriana (2) 5-6 pure white, solitary gray-green, prickly, early bloom  
callosa (1) 7 white spotted panicle, June blue-gray channeled leaves  
cochlearis (1) 6-7 pure white, June mounded clump of rosettes  
cotyledon (1) 5-6 fragrant white, arched flat rosettes  
cymbalaria (10) 6 yellow, starry low 2-4", for shade or dry crevice  
diversifolia (14) 6 rich yellow, few, racemes clump-forming for moist shade  
var. egemmulosa (3) 6 white,few green mats reddish in fall, hypnoides  
'Flower Carpet' 3 reddish pink 4-8" tall, from seed  
geranoides (3) 6-7 white bell-shaped cluster 8" tall, leathery, hairy, fragrant leaves  
grisebachii (2) 6 bluish pink, spike-like high-humped colony of rosettes  
hirsuta (5) 6 white, many in panicles long-stalked hairy basal leaves  
hostii (1) 6 white spotted, flat corymb quickly mat-forming  
hypnoides (3) 6 white, few loose mat to dense grass-like  
x irvingii (2) 6 lilac-pink, darker eye vigorous, spiny, gray-green, very early  
x kellereri (2) 6 pink, long branched stems gray rosettes, very early  
kingii: hypnoides var. egemmulosa        
kotschyi (2) 6 yellow, small in corymbs mounded, dense cushion  
'London Pride':x urbium        
x megaseiflora (2) 6 bright rose, solitary in 2-3s dwarf 1-2", gray hard cushions  
mutata (1) 5-6 yellow, orange panicle short-lived, rosettes die after flw.  
oppositifolia (4) 2-7 red shades flat cushion mats, variable site needs  
paniculata (1) 2-5 white umbellate panicles quickly mat-forming of rosettes  
x paradoxa (1) 5 cream white silvery cushion, natural hybrid  
pedemontana (3) 6 white, false umbel pale green carpet, leafy  
pensylvanica (12) 5 greenish white, small 2-3' tall, 1' leaves, for moist shade  
'Purple Carpet' 3 deep purple 3-4" tall, from seed  
'Purpurteppich':'Purple Carpet'        
rosacea (3) 6 white or pale pink, 2-5/stem variable habit with cultivar  
rotundifolia (11) 6 white, rose spots, floriferous 1-2' tall, bushy for moist shade  
x salmonica (2) 6 white, red buds, floriferous dense mats, short-lived  
'Snow Carpet' 3 white, large 5-7" tall, standard  
spruneri (2) 8 white, small, corymb small cushiony cluster  
stellaris (12) 2-6 white, starry, yellow spots requires gritty, moist, well-drained  
stolonifera (6) 5-6 white, red spots popular houseplant, thread-like stolons  
'Tricolor' (6) 5-6 white, red spots stolonifera, leaves green, white, pink  
umbrosa (5) 6-7 white, red spots usually mistaken for x urbium  
x urbium (5) 7 white, starry, small, red inner dense, dark green carpet  
valdensis (1)  6 white, June, small dwarf 1", hemisphere rosette  
'Variegata':'Aureopunctata'   x urbium    
veitchiana (6) 7 white to pink, few dark green above, brown below, stolons  
         


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

Return to  Perry's Perennial Pages | HGPO course | PSS123 course