The ultimate green thumb

Miller Garden curator and fern fancier Richie Steffen shared his frond enthusiasm with docents in an educational session.

Ferns have thumbs, Richie Steffen told us.  Well, some ferns have thumbs: those in the genus Polystichum, the group that includes the sword fern, that shade garden workhorse so well known to Northwest gardeners.  He further qualified that.  Most  of the Polystichum have the distinctive upward "ear" (indeed called a thumb) on the end of the "pinnae" (fern talk for leaflet) near the center stalk or "stipe."  Ferns are complicated plant forms and breakers of many rules.  As the Miller Garden curator explained some of the common distinguishing characteristics of various genera of fern he noted there are always exceptions.

In collaboration with longtime fern-expert Sue Olsen, Steffen has authored "The Plant Lover's Guide to Ferns,"  a photo filled and information dense volume covering 140 garden ferns, including the familiar and exotic.   Illustrating with handouts, buckets full of foliage samples and eventually a garden walkabout, Richie shared his expertise and enthusiasm for this enchanting plant form in an educational session for Dunn Gardens docents.

Another distinguishing characteristic of the Polystichum genus of ferns is the form of the "sori" or the capsules containing spores. As befitting these rather contrary specimens of the plant world, fern body parts comes with a vocabulary all their own, we learned.  Leaflets are "pinnae" and they are connected not to "stems" but to "stipes."   And to be in the know about ferns, one doesn't have to learn just one set of characteristics, but must be alert to multiple ways one genus differs from another.  To recognzie a Dryopteris fern, look for kidney shaped bumps (sori) on the backside.  If the fern might be an Athyrium, the bumps or sori will have a distinctive "J" shape, or maybe they will look like a crescent.  If it's an Adiantum, for example a Maidenhair, you will see instead of bumps, a kind of fold at the edge of the wedge shaped pinnae that encloses the spores in a "false indusium."   Blechnum, the genus that includes the beloved deer fern, are distinguised as "dimorphic" with erect, fertile fronds in the center of the whorl of fronds.

Whew.  And what's in a name?  More contradictions.  Common wisdom among plant folks is that botanical names are preferred over ever-changing common names.  But the Lady Fern is an exception.  Athyrium felix femina has been known by no fewer than 62 botanical names, but it's been Lady Fern all along.  And take Polystichium setiferum divisilobum.  It's known "locally" as the Alaska fern, and by locally we mean only in the United States.  It got that name because it was mistaken for the real Alaska fern, another plant entirely.

And don't even ask about the reproductive cycle of ferns.  As the advice columnists say, "It's complicated."  Making fern babies involves something that looks like a liverwort with a female and male end – in some cases only female – and requires water and a lot of time. 

Are you confused yet?  Richie says its okay.  Learn some fern vocabulary, don't worry too much about pronunciation and try to project confidence.  "Then you can make stuff up,"  he said.  Or you can read Richie's book.



  1. Christine Hill on May 26, 2016 at 7:01 pm

    Loved this program, and for

    Loved this program, and for the first time, begin to understand the fascination of ferns — Richie's enthusiasm was contagioius.