Otto von Bismarck, the powerful diplomatic deal maker of 19^th century Europe, is famously quoted as saying that politics is “the art of the possible.”  Horticulture, by contrast, could be defined as the art of the impossible or, to be precise, the seemingly impossible.  For instance, growing oranges in Alaska, you would think, is impossible.  However, as long as you have a heated greenhouse, you can grow oranges in freezing climates.

Or who would imagine that you could grow a tropical rain forest species upon the trunk of a drought toughened, California native tree?  Enter staghorn fern (Playcerium bifurcatum) and coast live oak (Quercus agrifolia).

I will never forget my first encounter with a staghorn fern.  I was wandering the grounds of the Huntington Botanical Gardens in San Marino.  Suddenly, I was confronted with a massive eruption of deeply lobed foliage cleaving to the trunk of a live – that is, evergreen — oak.  This particular oak tree, anyone could tell, was several hundred years old.  So what was that bizarre green appendage attached to it?  My first thought was that it must be an ornament of some kind or perhaps a parasitic monstrosity, sucking the life out of the aging oak.  Only later did I learn that it was a vibrant tropical epiphyte, thriving in the protective canopy of the oak.   An ephiphyte, it needs to be said, is a tree dwelling plant, a category that includes all staghorn species, most orchids and bromeliads, epiphyllums, and holiday cactus, too.

Shelly Fetterman, from Northridge, whose email inspired this column, sent me a picture of a staghorn fern that measures six feet top to bottom and has a circumference of 17 feet. It is growing on a board attached to a chain that hangs from her jacaranda tree.   “I know this fern grew from a spore,” she wrote, “because I remember when, 30 years ago, a tiny staghorn began to poke it’s little frond out of the side of a hanging orchid planter, eventually growing into what it is today. Since Northridge is probably as far away from a tropical rainforest as you can get, it is necessary to spray the staghorn daily, in the heat of the summer, but not for too long or it will rot.  I water it with a fan nozzle for just a few minutes at a time, simulating a tropical rain shower.  The staghorn wants its fronds to get rinsed, cooled off, and refreshed.  A couple of times a year I fertilize it with Miracid plant food when I am feeding the azaleas and camellias. Because this plant hangs in a tree and is so big it also catches much debris from above and birds even nest in it, so I’m sure it has it’s own composting going on in the middle.  I do have shade cloth hanging over it because in winter the jacaranda tree loses its foliage and we all know how hot and dry it can be right now.  The fronds will sun burn and can get pretty tattered in this contstant wind.  It is also very susceptible to freezing, but because it has some protection from the tree, the shade cloth, and constant air movement in my Northridge neighborhood, I have never had a problem with that.”

Although you don’t see them, staghorns do have roots, protected by basal leaves that cling to the adjacent board or tree trunk, and it is through these roots that they imbibe water and fertilizer.  The organic matter that Fetterman mentions, as it decomposes, does provide mineral nutrients which, dissolved in water, trickle down to the roots.

Speaking of tropicals, the following email, with accompanying photo, was sent by Richard Mueller, who gardens in Granada Hills: “I have a number of plumeria trees planted in my yard. There is one that I started from a cutting a few years ago that I have planted in the ground near the front entryway. I saw some flowers on it late last year, and now there is a strange growth emanating from the flower stem that looks like a seed pod. I have never seen any such thing over the last 30 years of growing plumeria plants. What do you think it is?”

Congratulations!  Yes, that long horizontal growth, precariously perched like a tightrope walker’s balance bar, is indeed a seed pod. It is extremely rare to produce a seed pod on a plumeria – that iconic Hawaiian plant whose fragrant flowers are strung together in leis — without benefit of artificial pollination and, even then, some plumerias never produce seed pods.  When a seed pod is formed without human assistance, it is a result of either self-pollination or thrips – a tiny, black threadlike insect – activity.  You can, however, attempt to personally (artificially) pollinate your plumeria flowers with a small artist’s paint brush. Plumeria, like the nearly all flowers, has both male and female flower parts so cross-pollination, the process by which new varieties are produced, involves transfer of pollen from the anthers of one flower to the stigmas of another.

Tip of the Week:  Frances Madrigal, who gardens in Glendora, sent me a photo of her Queen of Sheba vine (Podranea brycei/ricasoliana).  Given support, it will climb to twenty feet or, on its own, arch up to half that height.  It has the same climatic requirements as bougainvillea.  Inexplicably, it is almost never seen in our area, even while it produces huge bunches of pink trumpet flowers most of the year.