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Tuesday, August 12, 2014

Plant of the Month (August) : Catalina silverlace – Constancea (Eriophyllum) nevinii

Catalina silverlace (Constancea (Eriophyllum) nevinii; yellow flowers)
Mother Nature's Backyard

Last month we featured one of our loveliest silvery foliage plants – Perityle incana.  This month the whitest of them all, Catalina silverlace (Nevin's Wooly Sunflower), is blooming for the first time.  It simply begged us to be featured as our Plant of the Month.

 Like Perityle incana, Constancea nevinii is a member of the Sunflower family (Asteraceae), one of the largest plant families in California.  It was originally named  Eriophyllum nevinii (in the genus containing other native Wooly Sunflowers) and can still be found by that name at some nurseries.  Studies of plant DNA revealed that Catalina silverlace shares no common ancestor with the other Wooly sunflowers – in fact, it’s a more distant cousin.  In 2000 it was renamed in honor of Lincoln Constance, a well-known plant taxonomist, university administrator and former director of the UC Berkeley Herbarium.  The genus Constancea is monotypic; it contains a single species, Constancea nevinii.   For more about Lincoln Constance see: http://www.calflora.net/botanicalnames/pageCI-CY.html#Constancea

As with other Wooly sunflowers, Constancea nevinii has an extremely limited natural range, being found only on the Southern Channel Islands (San Clemente and Santa Catalina Islands) and the Northern Santa Barbara Island.  The Channel Islands, located just off the coast of central and southern California, are places of great biologic interest.  Like most islands, they contain unique species due to  their separation from mainland populations.  But the Channel Islands have several other unique features. 

Located at the edge of a tectonic plate, the Channel Islands have experienced extensive movement over millions of years, resulting in unique geologic and soil profiles.   As sea levels rose and fell, they were joined and separated from the mainland several times, allowing for species exchange.   Their close proximity has facilitated human visitation/habitation for at least thousands of years, resulting in further exchange of seeds/plants between islands and the mainland.  

The combination of these factors makes the California Channel Islands unique in their flora, fauna and geology; they are currently the subject of great scientific interest.   Unfortunately, many of the endemic species are now extremely rare, often due to human actions like hunting, farming and grazing.  Feral goats have played a particularly destructive role on several islands; their removal has been an important step in preserving native plants.   Interestingly, several island plant species (including Constancea nevinii) are well suited to gardens and are now used extensively in Southern California mainland gardens.

Catalina silverlace, a sub-shrub with woody stem, stands 2-5 ft. tall and at least as wide.  It closely resembles the ‘Dusty Miller’ (Jacobaea maritima/Senecio cineraria), a plant long favored for its white foliage and drought tolerance.  While Jacobaea maritima hails from the western/central Mediterranean region, it shares more than a superficial resemblance with Catalina silverlace.   Both grow in coastal areas, often on rocky coastal bluffs, in areas with a mediterranean climate.   Not surprisingly, both are known for their heat, salt and drought tolerance.   The two plants represent similar solutions to a shared set of environmental conditions.

Foliage of Catalina silverlace (Constancea (Eriophyllum) nevinii)
For comparison with Perityle incana see July, 2014

Catalina silverlace has a mounded, slowly spreading growth habit.  Its long leaves are finely dissected (see above) giving them a delicate fern-like appearance.  The foliage is covered with dense, wooly white hairs, making the foliage appear almost white.   These features help plants survive hot dry summers and are shared with species from other dry climates.  The low, mounded growth habit is often found among plants growing right on the coast.   This form is particularly suited to the wind and salt spray that dominate coastal landscapes.

Catalina silverlace (Constancea (Eriophyllum) nevinii) in bloom

California has native ‘sunflowers’ that bloom from early spring to late fall; Constancea nevinii is a mid-season bloomer.  It may flower anytime from April to August depending on weather conditions.   In our experience, adequate winter moisture is required for a good bloom season. 
Flowers, Catalina silverlace (Constancea (Eriophyllum) nevinii)

The flowers are bright yellow, adding a cheerful note to the summer garden.  On closer inspection, the flowers reveal their sunflower nature.  Flowers have central disk flowers surrounded by a few, very short yellow ray flowers (look like petals).  The individual flowers are small, but the heads are arranged in clusters of 20 to 50 on stalks above the foliage.  The entire effect is showy as seen in the photo above.

Catalina silverlace is a good habitat plant.  Pollinator insects are attracted by the flower’s sweet nectar and pollen.  Expect to see European Honey Bees, native bees, flower flies, butterflies and others visiting the flowers.   Seed-eating birds enjoy the seeds and small animals like lizards will shelter beneath the foliage.

Like the native bluckwheats, Catalina silverlace retains its beauty long after the flowering season has ended.  The flowering stalks, bracts and seeds turn a lovely dark brown that contrasts exquisitely with the white foliage.  In fact, many gardeners consider fall to be the prettiest season for this shrub.  The seeds are dry achenes that spread by wind. 

Catalina silverlace (Constancea (Eriophyllum) nevinii) in fall.

The ‘Island Silver’ cultivar is often available in local native plant nurseries.  A natural variant from Santa Barbara Island, ‘Island Silver’ was introduced by the Santa Barbara Botanic Garden and has grown there since the early 1980’s.   It has very white foliage and all the other characteristics that make this species so attractive.  It does well in local gardens and is a good alternative to the straight species.

Catalina silverlace is fairly undemanding in its requirements.   It prefers full sun along the coast, but is best with a little afternoon shade in hotter inland gardens. It is not frost hardy and can be damaged – even killed – by frost.  If you garden inland where frosts occur be sure to read our discussion last month: http://mother-natures-backyard.blogspot.com/2014/07/plant-of-month-july-guadalupe-island.html

Although preferring a well-drained soil, Constancea nevinii can be grown in clays.  If your soil is dense and compacted, try growing it on a slope or berm.   Once established, it needs very little supplemental water except in dry winters/springs. In Mother Nature’s Backyard we water it once or twice from May to August.     Plants will become leggy if not pruned back regularly in late fall or winter.  For fall pruning, remove spend flowering stalks and prune back the leafy stems, leaving 2-3 sets of new leaves.  This will result in a nice, mounded habit.

Catalina silverlace (Constancea (Eriophyllum) nevinii) against a backdrop of Littleleaf
 Mountain Mahogany.   Native Plant Garden, Madrona Marsh Nature Center, Torrance CA.

Gardeners from wetter climates often envy our native foliage plants – particularly those with very light-colored leaves.  Use Catalina silverlace to best advantage by growing it against an evergreen background of Toyon, Coffeeberry, Lemonadeberry, Sugarbush or Ceanothus (see above).   We also like to highlight spring annuals by growing them against a background of Constancea nevinii.  

The size and shape of Catalina silverlace make it a natural choice as an informal hedge or path border; it also functions well as a low foundation plant or in planters. It is relatively deer-tolerant and is good in fire-prone areas.   Consider planting it with California fuschia (Epilobium canum), Cleveland sage (Salvia clevelandii), native buckwheats (Eriogonum species) and native grasses.   It provides a touch white in a silver garden and is an elegant addition to a habitat garden.     And it is a constant reminder of the special – and rare -  plants native to our coastal islands.

For plant information sheets on other native plants see: http://nativeplantscsudh.blogspot.com/p/gallery-of-native-plants_17.html




We welcome your comments (below).  You can also send your questions to: mothernaturesbackyard10@gmail.com


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