Saturday, August 3, 2013

Only in SCV: Our Little Amazon's Rarest Gem

We have just entered the blooming period of one of the rarest species of plants on earth. It is called the Newhall Sunflower, though its scientific name is decidedly more captivating: Helianthus inexpectatus, “the unexpected sunflower.”[1] Fewer than ten individuals are known to exist the world over, and all are confined to a single, spring-fed seep near the Airport Mesa of Newhall Ranch.  The same seep produced another new species—the tiny Castaic Springsnail (Pyrgulopsis castaicensis)—just a few years ago.[2]  We might take for granted the existence of undescribed species haunting deep oceans or tangled rainforests, but who thinks of unknown life-forms lurking in Santa Clarita?  Is this seep our own tiny, verdant Amazon of sorts, brimming with the undiscovered?

Anuja Parikh and Nathan Gale have shared their photos of the Newhall Sunflower in the CalPhotos Database.  The sunflower is known from only one location, a seep in Newhall Ranch.

The Newhall Sunflower wasn’t the sort of plant that botanists immediately recognized as a new species, though they did immediately recognize it warranted special attention. In their 2010 paper describing H. inexpectatus, David Keil and Mark Elvin note that it was at first tentatively identified as the Los Angeles Sunflower, a subspecies long presumed extinct.  (You might remember an LA Times article from around 2002 proclaiming the rediscovery; it probably actually is extinct).  But multiple investigations of the sunflower’s genome—ranging from counting chromosomes to sequencing—revealed the sunflower was genetically distinct.  It appears to be most closely related to Nuttall's Sunflower, H. nuttallii, but it has unique morphological and genetic characteristics that warrant species status.

Keil and Elvin make some important points in their paper (emphases mine):
  • "The specific epithet [“inexpectatus”] refers to the unexpected discovery of this new species, its unexpected status as a tetraploid, and its unexpected apparent lack of a close relationship to H. californicus."
  • "Because of its remarkable geographical restriction, population size (fewer that ten individuals known), and threats, the Newhall sunflower appears to meet the criteria necessary for listing under both State and Federal Endangered Species Acts."
  • "It flowers from August to October. Helianthus inexpectatus grows in a shallow seep (approximately one acre in size) that appears to be fed by at least three springs at the base of a ridge. […] The seep is directly adjacent to lands slated for development as part of a master-planned community that would include an estimated 20,000+ homes and a bridge that is proposed to be installed within 100m of the seep."
This all puts the plant is in a curious place.  It’s not listed by the State/Feds as an endangered species yet—they didn’t even know the species existed until a couple of years ago—so it doesn’t have the formal legal status of something like, say, our “officially” endangered spineflower.  The California Native Plant Society is more nimble than governmental agencies, however, and has classified the Newhall Sunflower as “seriously endangered” and “critically imperiled.”  A plant can’t get any rarer than that, and this categorization affords it some protection.    

According to the literature, Newhall Sunflowers should be in bud this time of year and ready to bloom later this month.  Since the species' only known stronghold is on Newhall Ranch and off-limits to the public, there won’t be any rare plant safaris, so to speak, for those who would like to see it.  And that may well be for the best.  But if you’re the sort who likes to wander through the Santa Clara River, keep an eye out for a rather leggy sunflower growing in wet spots.  It’s most likely to be Nuttall’s Sunflower, and it's not always possible to distinguish one Helianthus from another.  (For some helpful hints, though, read Footnote 3.) I may be overly optimistic, but I like to think some more Newhall Sunflowers might be growing in another wet, willowy spot along the Santa Clara River.  And with the delay of the Newhall Ranch development, we might have more time to ensure it persists.
[1]The paper that informs this post can be viewed here: Keil, D.J., Elvin, M.A. 2010. Helianthus inexpectatus (Asteraceae), a tetraploid perennial new species from southern California. Aliso: A Journal of Systematic and Evolutionary Botany, 28:59.
[2]Do you like obscure, minute aquatic snails?  Then you'll  love reading this paper: Hershler, R., Liu, H.P. 2010. Two new, possibly threatened species of Pyrgulopsis (Gastropoda: Hydrobiidae) from southwestern California. Zootaxa, 2343:1-17.
[3]Experts on this sunflower warn that it may not be possible to identify it in the field.  Many of its characteristic measurements fall close to those of other species.  But in its treatment of the genus, The Jepson Manual/eFlora recommend looking at the phyllaries--the stiff, green, petal-like structures that lay beneath the flower disc--to tell one from another.  If the phyllaries are 3-5mm wide and bend downward at the tip, it' H. californicus.  If the phyllaries are 1-1.5mm wide and point upward, it's H. nuttallii.  But if the phyllaries fall somewhere in the middle at 2-3mm wide, it just might be H. inexpectatus.  So when you wander along the Santa Clara River, carry a millimeter ruler and remember this rule: broad, saggy phyllaries are californicus; narrow, erect phyllaries are nuttallii; and H. inexpectatus is intermediate in phyllary width and "posture".  Below, it's californicus left, nuttallii center, and inexpectatus right.


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