Sunday, December 13, 2015

Bullet Proof and Blingy! Holly-leafed Cherry - Another Excellent California Native

If you are one of those people that say growing California native plants is difficult, try the evergreen
hollyleaf cherry, Prunus ilicifolia ssp. ilicifolia. Read on, if you want to know why I think this is one of best plants for your garden. Looks are deceiving as this shiny-leaved, almost delicate-looking evergreen small tree is one of the toughest members of my plant posse. Check out these gorgeous leaves (Figure 1). Did I say blingy? Why yes, yes I did! Sparkly and blingy! I love this plant!
Figure 1 Prunus ilicifolia ssp. lyonii leaves                                                                                                                                  S. Reeve

Botanical Classification  

The genus Prunus is in the Rosaceae, and more specifically, the subfamily of Prunoideae, which is characterized by having one simple pistil with one superior ovary. Fruits are a stone fruit or drupe with one seed surrounded by a hard coat. The genus Prunus has flowers that are 5-merous, in other words, with five petals, five sepals, and other floral structures (stamens) in multiples of five (Figure 2). Flowers are arranged in a 2" long raceme with many flowers (Figure 2). Plants start blooming around three years of age in the late spring. 

  Figure 2 Prunus ilicifolia ssp. ilicifolia raceme of flowers                                                                                Marc Kummel

Evergreen simple leaves of Prunus ilicifolia ssp. ilicifolia are deep green, with a paler underside, around two inches long, alternate, oval to round, serrate with coarse spines and sometimes with wavy leaf margins, and very glossy (Figure 1). Cherry fruit ripens in the early fall and can range from red-to-black and sometimes yellow (Figure 3).

   Figure 3. Prunus ilicifolia ssp. ilicifolia fruit    

Prunus ilicifolia Subspecies Distribution and Characteristics

Prunus ilicifolia has two subpecies Prunus ilicifolia ssp. ilicifolia (Figure 4) and Prunus ilicifolia ssp. lyonii (Figure 5). For the ranges below I used Calflora maps and recorded the area where there were substantial populations. For the Baja populations, I relied on descriptions from the  Baja California Plant Field Guide by Jon Rebman. (I usually use Adobe InDesign to do page layouts and this is in Google Blogger and I have no idea how to get these maps to line up. Blogger just seems to do stuff for no reason). 

Prunus ilicifolia ssp. ilicifolia has a larger distribution. Hollyleaf cherry is found predominantly in coastal chaparrel, coastal scrub, and oak woodland ecosystems with scrub oak, coffeeberry, and toyon on both moist and dry slopes, up to 5000 feet in elevation, from Napa County down into the upper third of Baja California. Prunus ilicifolia ssp. ilicifolia is a generalist plant and further north it is found in a number of communities, including alluvial scrub and desert transition. In Baja, it occurs up to 1500 feet in elevation. Further south it occurs more on northern slopes and canyons that tend to be moister environments or near water. Growth habit of Hollyleaf cherry is variable and wholly dependent on the presence of water. Plants with rich well-drained soil near sources of water become tree-like while those in my arid situations stay small shrubs. Hollyleaf cherry attains the largest sizes in canyons with sandy moist soil. A few stragglers are found even further south than shown on the map but only in ideal conditions (Figure 4). 

Subspecies Prunus ilicifolia ssp. lyonii occurs predominantly on the larger Channel Islands, but also on coastal Southern California, and populations also exist in the central postion of Baja California (Figure 5). Prunus ilicifolia ssp. lyonii occurs at lower elevations, up to 1800 feet in elevation. How the populations got so far away from each other is a mystery. I wonder if native peoples moved Prunus ilicifolia ssp. lyonii from the Channel Islands to the mainland and down into Mexico?


Figure 4. Prunus ilicifolia ssp. ilicifolia range                               Figure 5. Prunus ilicifolia ssp. lyonii range 

Prunus ilicifolia ssp. ilicifolia differs from Prunus ilicifolia ssp. lyonii in several different ways. Prunus ilicifolia ssp. lyonii, also called Catalina cherry, is a much larger plant, and definitely a tree (Figure 7).  The photograph in Figure 7 was taken on Catalina Island near Two Harbors in a location called Cherry Cove. As you can see these are trees that can get large, and eventually can attain 45 feet in height. The leaves are also quite different from Hollyleaf cherry, in that, there are no spines, and the margins are entire. Studies suggest, that in the absence of grazing animals, the island subspecies did not need to develop the evolutionary strategy of spines to thwart herbivory. The foliage is softer and less shiny and the margin is not wavy like most members of Prunus ilicifolia spp. ilicifolia. Catalina cherry also has larger fruit and longer petioles than Hollyleaf cherry. The bark differs as well, with Prunus ilicifolia ssp. ilicifolia having dark grey and smooth bark that becomes fissured with age, and Prunus ilicifolia ssp. lyonii having rough-seamed fissured bark that is colored dark reddish brown. Keep in mind these two subspecies hybridize readily, so it is sometimes difficult to distinguish if you have a straight subspecies in the field. 

     Figure 6. Prunus ilicifolia ssp. lyonii leaves

     Figure 7. Prunus ilicifolia ssp. lyonii trees at Cherry Cove near Two Harbors, Catalina


This topic has been covered very well in a number of publications and could be an article in itself. Suffice it to say, Hollyleaf cherry was very important to the coastal native people of California. I do want to add what I found when I was researching my senior thesis while earning my BA in Landscape Architecture. Hollyleaf cherry was originally called "Slay" by the Salinan tribe of California native Americans.  The name changed under Spanish influence to "Islay", and the name was widely used and incorporated into the Spanish vernacular of place names where Islay cherry trees abounded. In San Francisco, the Muwekma Ohlone Tribe, harvested the bounty of Islais Creek, for several thousand years. A population of Islay cherry trees thrived there in the Bernal Heights area of San Francisco (Figure 8). In San Luis Obispo there was "Islay Creek" and "Islay Hill." 

    Figure 8. Historical location of Islais Creek watershed in San Francisco                                                               unknown

Native Americans prized the shelled seeds of the Islay cherry more than acorns. Unlike grocery store cherries where the pulpy mesocarp is eaten and the pit thrown away, the pit of the Islay cherry is what was primarily eaten. Some tribes were reported to eat the flesh (Kumeyaay), but the flesh is relatively skimpy and not valued. In the records, various tribes had various methods for preparing the seeds for eating.  Cherry pits contain cyanogenic glycosides, specifically amygdalin and prunasin, which are converted in digestion to toxic compounds. When crushing the leaves, an almond smell can be detected which is evidence of prussic acid (prunasin) content in the leaves. In the watery environment of the digestive track these compounds break down to form hydrocyanic acids containing hydrogen cyanide (HCN) which are toxic in sufficient quantities. In food preparation, after removing the pulp, the seeds were shelled and either roasted, ground, boiled, leached with water, or a combination of treatments, to remove the toxins and the bitterness. HCN volatilizes readily when the seeds are dried or treated. Most native tribes used the mashed ground pits as a meal to make a cake, and some tribes, like the Kumeyaay, made a porridge. Sometimes it was sweetened, and often combined with pinole flour or grass seed to form a reddish cake, that was said to taste like beans.

Other ethnobotanical uses for Prunus ilicifolia include making a green dye from the leaves, and using infusions of either bark, roots, or leaves as cough medicine. The toxins act as a muscle relaxer and are also said to improve digestion in small amounts. Infusions were also used for headache relief and for an eyewash. The fine wood of cherry was used to make bows for hunting. One of the most important uses of the Islay cakes were for socializing with vistors. 

                           Figure 9. Prunus ilicifolia ssp. lyonii                                                                         S. Reeve

Prunus ilicifolia in the Landscape

I have Prunus ilicifolia ssp. lyonii in my landscape. After three years it is 7 feet high and 6 feet wide, from a gallon pot. This is its third year and I am seeing an acceleration of growth. It initially received regular water but no longer. This plant becomes more drought tolerant with age. The plant seems to be forgiving of watering errors. It takes summer water, which, for many California natives is a death sentence. The foliage is gorgeous, to a leaf, and it doesn't seem to have much insect damage. The plant I have is in light shade to full sun and the soil is fast-draining and rich sandy loam. I seemed to have hit upon the magic set of conditions. I am thinking it may bloom this year! The plant tolerates shade and full sun, but I think light shade is best here in San Diego. The plant seems to be long-lived with some specimens reaching 100 years. The shrub or tree is also very good at stabilizing slopes. 

This durable plant suits a wide range of landscape treatments. It makes a fine clipped hedge, a free-form mixed hedge with other native plants, a standard, or trained as a small tree. Bad views? Use this plant as a screen. The width can be maintained so it can develop height. Just be aware the fallen fruit stains concrete, so position it accordingly. Also, if size must be controlled, use hand trimmers to avoid the chewed up foliage look that results from powered hedge trimmer use. Training to a single trunk may require frequent trimming of root sprouts--don't say I didn't warn you! Prune in July. Young trees are not frost tolerant, but become increasingly so with age, down to zero degrees F. 

Although, this is an actual drought tolerant desert transition plant, it does look out of place with other desert plants. Next to Toyon, Quercus dumosa, Rhus intergrifolia, Frangula californica, or Sambucus would be more appropriate. An especially choice combination is with a red-tinted Arctostaphylos like 'John Dourley', 'Sunset', or Arctostaphylos pajaroensis. If the manzinita is trimmed to expose the peeling trunks the beauty would be showcased in front of the glossy green of the cherry. Nice!

Uses for Prunus ilicifolia ssp. ilicifolia are similar. It is said that a straight subspecies of Prunus ilicifolia ssp. lyonii no longer exists in the trade, and all have varying degrees of Prunus ilicifolia ssp. ilicifolia in their lineage.

Wildlife Gardening 

If you have a wildlife garden you must have this plant! A long list of organisms benefit from its inclusion in the landscape. Hollyleaf cherry can even be used in a highly urban garden to attract birds, bees, and other creatures. 

Flowers are highly valued for pollen and nectar, when blooming in April-May, by honeybees, and native bees in the genera: Ceratina, Habropoda, and Osmia. Native bumblebees (Bombus) also visit the flowers. 

A long list of Lepidoptera nectar on Hollyleaf cherry including Western Tiger Swallowtail, Anise Swaallowtail, and Pale Swallowtail, California Sister, Lorquin's Admiral, Red Admiral, California Tortoiseshell, Variable Checkerspot, Edith's Checkerspot, Brown Elfin, and Hedgerow Hairstreak and many others. Moths visit the plant for nectar at night. Many butterflies and moths have evolved to use the plant as a host plant. Butterflies include Western Tiger Swallowtail, Pale Swallowtail, Echo Blue, and Coral Hairstreak. A very long list of moths use Prunus as a host plant. Ants, flies, lacewings, and wasps all visit Prunus blooms. Beneficial insects all visit Prunus looking for prey.

The plant itself offers shelter or nesting sites for many species of birds like towhees, wrens, warblers, sparrows, finches, bushtits, juncos and quail. For some birds, though, the ripe fruit is the draw. Robins, finches, cedar waxwings, and towhees enjoy the fruit and spread the seeds. Woodpeckers visit to find insects. Small mammals, coyotes, and rodents eat the fruit. Leaves are browsed by deer, and bighorn sheep, although, maybe not in your yard. 

Propagating Prunus ilicifolia 

Fresh seed germinates easily if you remove the mesocarp (pulp) first. Collect the ripened fruit in early January (Betty Young), or when you see fully ripened fruit, could be in the fall. Cover fruit with water and mash the fruit to loosen the skins and allow to ferment for easier removal of the pulp. You can make this process easier if you get an old blender and wrap duct tape over the blades. Place seeds in blender and cover with water. Pulse to remove pulp, and allow to sit for several days so fermentation can take place. 
Here is a kitchen method to remove pulp, place fruit in the largest zip lock bag, and leave enough room for enough water and air, and put enough water to cover. Allow the bag to sit outside and ferment. You can squish the contents with your hands to hasten the separation of seeds. Alternatively, rub seeds over a screen to scrap away pulp- messy.  Remove pulp and plant seed as deep as the seed is large in tree tubes with planting mix. Otherwise, after removing pulp, thoroughly dry the seeds and store in the refrigerator. Stored seed will need cold stratification to germinate. Soak stored seeds in water overnight then place in baggie with moistened perlite and put back in the refrigerator. Seeds should germinate in 1-3 months. Remove germinated seeds and plant in tree tubes with planting mix.

If you do not have this plant in your yard and you call yourself a "wildlife gardener" you are committing a crime against nature. Go get it!

----------------------------I easily use 40-100 sources to research these articles-------------------------------