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Monday, February 6, 2017

Plant of the Month (February) : California polypody fern – Polypodium californicum


California polypody (Polypodium californicum) - leafing out in Mother Nature's Garden of Health

My, how it’s rained recently; almost 9 inches in January alone.  That’s as much as we sometimes get in an entire year!  The ground is really moist, and some of our perennials are looking the best they have in years.  Coming into its own right now is the one native fern we currently grow – the California polypody, Polypodium californicum.  The scientific name is pronounced pol-ee-PODE-ee-um   ka-li-FOR-ni-kum.

California polypody is a member of the Polypody fern family (Polypodiaceae), a large family of ferns with about 40-50 genera and 500-700 species worldwide. At one time, many more ferns were included in the family and the exact numbers are still debated.  Most polypodies grow in moist climates, commonly in rainforests.  The majority are also epiphytes (plants that grow on other plants, rather than in the soil).  That makes California polypody unique on two accounts: it grows in a mediterranean climate and it grows in the ground.

Ferns are placed in a separate division of the Plant Kingdom (Pteridophyta). Pteridophytes are ancient plant forms that do not produce seeds.  Their life cycle involves alternating generations of sporophytes (what we commonly think of as the ‘ferns’) and gametophytes (small, moss-like plants).  Reproduction depends on water; sperm can only reach eggs to fertilize them via water.

Sporophytes produce tiny spores in small, rounded sori on the bottom surfaces of the leaves.  The spores, given moist growing conditions, develop into the gametophye generation, which produces eggs and sperm.  Fertilized eggs, when they occur, then give rise to new sporophyte plants. For more on ferns and their reproduction see references 1 and 2, below.

California has five native Polypodies. [3]   Only two are native to Southern California: California polypody and Western polypody (Polypodium hesperium).  California polypody has a natural range from the Northern California coast to the coast of Baja California, Mexico.  It grows in shaded canyons, along streambanks, on rocky, north-facing slopes, in rock crevices and on cliffs/coastal bluffs.  It can still be found in the coastal sage scrub and chaparral communities of the Santa Monica and San Gabriel Mountain foothills and on the southern Channel Islands, at elevations below about 4000 ft. (1500 m.).

California polypody (Polypodium californicum) - frond (leaf)
 
California polypody is a small, herbaceous perennial fern.  Its sporophyte generation grows 1-2 ft tall (usually 6-12 inches, but may be taller in garden) and about as wide.   Like most ferns, its leaves (called fronds) are compound, with many leaflets (called pinnae in the ferns) along a stout, hairy midrib.  The fronds are fairly simple, being only once pinnate.  The pinnae have rounded tips and are minutely serrate.  The sori develop on the underside of the pinnae; the indentations of the sori can be seen from the upper side in young leaves (see above).

Plants spread slowly via stout underground stems (rhizomes). The rhizomes have many knobby projections, alluded to by the scientific name (poly = many; pody = feet). Plants die back to the ground in the dry season (summer/fall).  New fronds appear with the winter rains. 

California polypody is a nice fern for the garden.  Its small size makes it appropriate for even small spaces.  While preferring a well-drained soil, Polypodium californicum can be grown in most S. California soils.   It will tolerate morning sun, dappled shade or quite shady conditions.  It likes good winter/spring moisture, but then needs to dry out by late summer/early fall.  You can water it once a month or so in early/mid-summer and plants are fine with winter flooding.
 

California polypody (Polypodium californicum) - in shady garden
 with sedges, Mugwort (Artemisia douglasiana)
 
Ferns don’t ask for much in the way of management.  Trim off dead fronds for neatness – that’s about it.   You can grow Polypodium californicum just about anywhere with some shade and late summer dry.  This is a cute one for a porch container.  It’s charming with shade-tolerant Carex, Heucheras, Columbine (Acquilegia) and other perennials with similar requirements.   It’s often used in moist rock gardens, rocky slopes and fern grottos.  But it can even do well in the dense shade under native oaks and other trees.
 


'Sarah Lyman' polypody (Polypodium 'Sarah Lyman') - leaves
 are quite showy

A fern often sold as Polypodium californicum ‘Sarah Lyman’ or Polypodium calirhiza 'Sarah Lyman' is actually a hybrid between Polypodium californicum and P. hesperium.  This cultivar has all the characteristics of California polypody, but its leaves are ruffled and much showier.  It’s a little charmer that’s widely available from California native nurseries and online fern sources.  We’ve grown it and love it!

The young fronds (fiddlenecks) can be eaten, raw or cooked, fresh or dried.  Native Californians used the roots in the treatment of coughs, chest soreness, and the pains of rheumatism.  Plants were also used as a laxative and for skin wounds.  This is not a major medicinal plant, but was useful enough to include in our Garden of Health.
 


California polypody (Polypodium californicum) -
S. California native fern
 
Native ferns are an interesting addition to local gardens.  While not as important food, habitat or medicinal plants as other natives, they add a particular charm and personality to the shady garden. We love the idea of creating a Victorian fern grotto using California natives – perhaps we’ll do so sometime.  As perennials, Polypodies die back each year, but then reappear with the rains as if by magic.  It’s such a joy to see the new fronds unfurl each season.   Are you hooked yet?

 

For a gardening information sheet see: http://www.slideshare.net/cvadheim/polypodium-californicum


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

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  1. http://www.anbg.gov.au/fern/life_cycle.html
  2. http://amerfernsoc.org/lernfrnl.html
  3. http://www.calflora.org/cgi-bin/specieslist.cgi?where-genus=Polypodium

 
 

 

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

 

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