Silphium and Friends – Still Crazy…

Silphium and its allies are a team with modest representation in the Apalachicola flora, each being something of an outlier from a somewhat distant center of diversity.  Follow with me as we review the four genera, which are our only native taxa classified as closely related members of the Silphium sub-tribe, designated by Steussy (1977) as the Engelmanniinae.

Silphium compositum in Apalachicola National Forest

SilphiumCurrently recognized as comprising 16 species native to Eastern and Central North America, Silphium is represented in the Apalachicola flora by Silphium compositum and Silphium asteriscus.  Asteriscus is the senior member of this pair taxonomically, having been named in Linnaeus’s first edition Species Plantarum as one of four species known for this North American genus.  The readily-identifiable Silphium compositum was described by Michaux, in his 1803 Flora Boreali-Americana.

Flowering Head of Silphium compositum

ChrysogonumChrysogonum virginianum also has been around since before 1753, as one of two species Linnaeus included in his Species Plantarum treatment of the genus (the other was from Peru).  The Florida plant has been documented from four surrounding northerly counties (Walton, Jackson, Gadsden, and Leon) – represented by variety australe, which has been identified from Louisiana, eastward along the upper Coastal Plain into Alabama and Georgia, while the typical variety is native from Kentucky and the Carolinas northward. Some publications suggest the southern variety might be treated as a separate species, but that hasn’t been accepted. 

Circumscription of Chrysogonum, with less than ten species, is curious.  About half of the taxa are thought native to the Eastern US, while the others are described from Madagascar – which (to me) isn’t credible.  Madagascar?  Really!  A place known for endemism; home of some of the most amazingly distinct plants and animals, reflecting evolutionary distance from other flora and fauna?

Berlandiera pumila, note the white pubescence on foliage of this specimen
Berlandiera pumila
Berlandiera pumila, from flowering to fruiting. Note seed (achenes, 1-seeded fruit) form only around the perimeter

Berlandiera We know Berlandiera in Florida by two species, Berlandiera pumila in the Apalachicola flora, and the endemic B. subacaulis further South.  These two species are complemented by a pair of more western plants (in the southern tier states, west of the Mississippi River).  Augmenting the four species, Pinkava’s Flora North America treatment also recognizes three hybrid taxa, suggesting his study revealed considerable variation across the range.  The Apalachicola representative is an upright plant of sandy, relatively drier sites recognized by green bracts nearly obscuring the sterile disk florets, a characteristic related to the plant’s common name – “Soft Greeneyes”.

Prominent green bracts in the disk color the flowering heads green

Borrichia — If you are at the shore and find a weathered daisy with thickened obovate to oblanceolate leaves and a straggly, somewhat lax habit, growing among reeds, you may be looking at Borrichia.

Borrichia frutescens young flowering head

Our native marsh daisy  Borrichia frutescens, is the only northerly Borrichia of three currently recognized species in the genus, the other two being the Caribbean Borrichia arborescens (which can be found from Broward County south.) and a South American species.  The plant is readily recognized to genus, and if you encounter it here in the Apalachicola region, B. frutescens is the only game in town. 

Borrichia frutescens inflorescence
Borrichia frutescens foliage among the marsh reeds

It occupies a very narrow habitat, intermingled with marsh reeds and grasses, right at the marine interface.  In my limited experience, plants aren’t abundant, though widespread, having been identified in nearly every coastal Florida county, as well as marshlands from Texas to Virginia. 

Leaving Borrichia aside, the other species in this group will be encountered on drier land, in lightly-canopied forest, meadows and clearings, edges, and gardens. It’s a short list to encounter — two Silphium species, a Berlandiera, and potentially a Chrysogonum.  Additionally, in nurseries, you might spot the Florida endemic Berlandiera subacaulis and almost certainly will find Compass Plant, Silphium laciniatum,  a native to the Mississippi and Mobile watersheds (but not reported as natively present Eastward, in Florida. )

Flower Heads of Helianthus annuus (left) and Silphium asteriscus (right)

The main challenge in recognizing these plants is that they are DYC – damned yellow composites.  They look like so many other of their distant Sunflower relatives, producing leafy involucral bracts (phyllaries) and receptacular bracts (palea, or chaff) subtending florets, ray flowers that are fertile (and in all but Borrachia, with central disc flowers that are sterile).

Involucres of Helianthus annuus (left) and Silphium asteriscus (right)

Utilizing keys in the Flora of Florida, Volume 7 (2020), we arrive close to identifying the genera through the following dichotomies:

  1. “Radiate capitulae”  – Flowering heads of all four genera include both ray and disc flowers, with rays being yellow.  These features direct you to Key 2, a bastion of yellow daisies.
  2. “Receptacle with pales.”  In Key 2, this dichotomy eliminates half of the DYC genera (such as Helenium, Packera, Chrysopsis, Heterotheca, Pityopsis, Tagetes, and Solidago), leaving almost everything you’d imagine being related to Sunflowers.
  3. “Disk flowers sterile”.  This dichotomy segregates Silphium, Berlandiera, and Chrysoganum (along with 4 genera) from most of the Sunflowers.
  4. That leaves Borrichia with plants having fertile disk flowers.  The genus falls out as having fertile (carpellate) ray flowers (which is characteristic of the sub-tribe).  Borrichia is then segregated from other Sunflowers in having clasping, folded pales, opposite leaves, and a shrubby habit.  But dichotomous keys fail to point out the unique habit,  habitat, and foliage that a field botanist would instantly recognize.

The best hope for distinguishing Silphium, Berlandiera, and Chrysogonum from other similar composites is knowing that the disk flowers are sterile.  That may not be a convenient or simple character for casual recognition.  So what other characteristics might be helpful?  At first glance these are among the many yellow-flowered daisies, but like Goldilocks’ choices, they’re just right, all in a “medium” size class. If the spread of rays that highlight the flowering head is less than the breadth of a pingpong ball, it’s probably not one of these plants.  And if the spread is much greater than the diameter of a baseball, once again, probably not among this sub-tribe in Florida.  If there are a lot of rays, more than 20, you are likely not in this group.  Only Silphium asteriscus may have as many as 20 rays with a spread of 3”, but Silphium compositum, Berlandiera, and Chrysogonum, which might show as many as 12 rays, typically produce less than 10. 

Silphium asteriscus flowering head
Berlandieria pumila involucre

Another clue comes from the rounded, soft-textured involucral bracts that form in 2-3 series, cupping around the florets and remaining conspicuously persistent once ray florets are shed.    

Distinguishing between Silphium and its erstwhile congener Berlandiera is not so simple. The core reasons botanists have segregated Berlandiera relate to technicalities that don’t make good field characters, like chromosome number (2n =14 in Silphium, vs. 2n = 30 in Berlandiera.) The main dichotomy I see in floristic keys requires knowing whether the achenes form on the outer 2-3 series of florets in a flowering head versus in the outer series only. That doesn’t work out for me. Thankfully, the small numbers of species in our flora, and their vegetative and involucral distinctiveness makes it simpler.

The Back Story of Sub-Tribe Engelmanniinae
This modest-sized clade or cluster of Composites isn’t ridden with complex histories characteristic of so many other genera, though it has it’s odd moments, which begin with the generic name Silphium.  Linnaeus elected to apply this name to the generic grouping of four plants from North America, even though the word comes from Mediterranean antiquity as the name for a valued medicinal herb – a noteworthy plant of lost identity.  Look up the term Silphium and you’ll run into a host of articles, including a significant Wikipedia entry, all focusing on the mystery of the plant.  

Here are a few lines from Wikipedia:  Silphium (also known as silphion, laserwort, or laser) is an unidentified plant that was used in classical antiquity as a seasoning, perfume, aphrodisiac, and medicine.  It also was used as a contraceptive by ancient Greeks and Romans.  It was the essential item of trade from the ancient North African city of Cyrene, and was so critical to the Cyrenian economy that most of their coins bore a picture of the plant.  The valuable product was the plant’s resin (laser, laserpicium, or lasarpicium).
Silphium was an important species in classical antiquity, as evidenced by the Egyptians and Knossos Minoans developing a specific glyph to represent the silphium plant. It was used widely by most ancient Mediterranean cultures; the Romans, who mentioned the plant in poems or songs, considered it “worth its weight in denarii” (silver coins), or even gold. Legend said that it was a gift from the god Apollo.
The exact identity of silphium is unclear. It was claimed to have become extinct in Roman times.  It is commonly believed to be a fennel relative in the genus Ferula, perhaps a variety of giant fennel. The extant plants Margotia gummifera,[ Ferula tingitana, and Ferula drudeana have been suggested as other possibilities. Another theory is that it was simply a high quality variety of asafetida, a common spice in the Roman Empire. The two spices were considered the same by many Romans including the geographer Strabo.  In 2021, a study from Istanbul University identified Ferula drudeana as a likely candidate for Silphium, matching both the appearance of Silphium in descriptions and the spice-like gum-resin of Silphium, though without a surviving sample no genetic analysis can be made.”

Perhaps the resinous character that gives rise to the common name Rosinweed inspired use of the name Silphium, since the resin of the Ancient herb was its most valued product.  I haven’t discovered any absolute reason, but following the trail, it is clear that as early as 1737 (in Hortus Cliffortianus) Linnaeus decided to reuse the name Silphium for this group,  which being North American has no relationship to the historical Mediterranean herb.  But Linnaeus had two personal issues going – he had definite opinions as to what sorts of words are appropriate for genera, and he was attempting to consolidate the growing morass that plant nomenclature became as the world’s botanical biodiversity was arriving in Europe.  Basing his concept for the new genus on a plant Dillenius named and illustrated as Asteriscus, (which he had adopted from Tournefort), Linnaeus elected to us that term as the specific epithet for his newly anointed Silphium, generating the taxonomic lineage for the plant we call Silphium asteriscus today.

Plate 37 from Dillenius, cited by Linnaeus in his description of Silphium asteriscus

Michaux, well-aware of earlier literature, encountered plants in his travels that he assigned to the Linnaean genus, describing Silphium compositum, Silphium integrifolium, and Silphium pumilum in his 1803 Flora boreali-Americana.  The works of many botanists, from Tournefort and Ray to Linnaeus and Michaux became fodder for Swiss botanist August Pyramus de Condolle, who published his first works in botany at the very time Michaux was completing his Flora, and about to leave on the journey that would end his life.

De Condolle truly changed the botanical landscape, coming to age as successor (and predecessor to future attempts) among a series of botanists who strove to comprehend and catalog the world’s plants, from the Bauhin brothers, to Tournefort, Linnaeus, Adanson, and de Jussieu.  His Prodromus, though incomplete (as all world floristic compilations have been) established a more refined sense of order.  Volume 5 dealt with Order (read Family) 102, the Composites.  In a sweeping treatment, de Condolle laid out the organization, with Tribe IV being Senecionideae, comprising eight subtribes: Melampodineae, Heliantheae, Flaverieae, Tagetineae, Helenieae, Anthemideae, Gnaphalieae, and Senecioneae.  His first Subtribe, Melampodineae, includes 7 Divisions: Euxenieae, Millerieae, Silphieae, Melampodiaeae, Ambrosieae, Iveae, and Parthenieae.  

Focusing on his third Division, the Silphieae, we find De Condolle’s 6 numbered genera:

  • CCLXXIX Guardiola
  • CCLXXX. Hidalgoa
  • CCLXXXI. Silphium
  • CCLXXXII. Polymnia
  • CCCLXXXIII. Espeletia
  • CCLXXXIV. Berlandiera

The last, Berlandiera, is newly described on page 517 of Prodromus, honoring Berlandier and including the single species, B. texana.  So why Berlandier?  

Read the Wikipedia entry for Jean-Louis Berlandier ( and you’ll learn he was recommended by his mentor, Auguste Pyrame De Candolle, to serve  as biologist for an expedition in Mexico.  Arriving in Veracruz in December, 1826, Berlandier would remain in the country through the remainder of his life (1851), becoming a significant Mexican botanist and physician, as well as a political and cultural force in the new republic.  At least 16 plant and animal taxa have been named for him.  Texas botanists are, I believe, right proud of him, even though he fought on the side of Mexico in the 1846 “hostilities”, and served as a Mexican representative on the International Boundary Commission that defined the border between Mexico and the US.  Perhaps botanists are not so constrained by political boundaries. One thing is certain; Berlandier earned his genus, in all regards.

Earlier, I described Berlandiera pumila as an erstwhile Silphium congener, but that’s true for both of the Florida species. Michaux had described Silphium pumilum (published posthumously) in 1803. Many years later, Thomas Nuttall, working in Philadelphia, described another new Silphium, S. subacaule, in an article detailing plants of East Florida, collected by A. Ware in October through November, 1821.

The Nuttall article bears attention, for many regards. An historical note is his open expression of annoyance with Fothergill, who, Nuttall suggests, was hoarding Bartram’s collections: “The first enterprising naturalist who visited this delightfully temperate region, was our venerable friend Mr. William Bartram, of Kinsessing, but unfortunately for science, his collections have been consigned to oblivion, though still, I believe, existing in the Banksian herbarium. Doctor Fothergill, his patron, being rather an amateur than a successful cultivator of natural science, never brought forward the result of Mr. Bartram’s labours.”

Another, somewhat sardonic moment comes in his description of the Silphium, in which Nuttall notes: “Flowers, as usual, yellow.”

Working in Philadelphia was important for Nuttall, in that taxonomy is citation-intensive. For this kind of work to have meaning, a significant library is crucial to keep up on “the literature.” By 1840, Nuttall responded to the 1836 De Candolle publication (Prodromus...) of the genus Berlandiera in reassigning Michaux’s Silphium pumilum and his own Silphium subacaule to that newly minted genus. (I encourage you to search Thomas Nuttall on Wikipedia – his was a truly fascinating series of life events, ending in a very British manner)

On Borrichia….

We’ve encountered Adanson before, the man who labored in near poverty to complete his enormous dream of charting the world’s plants in a natural system of organization.  By natural, he insisted plants be grouped by their many points of similarity rather than the stress on numbers and relative union of stamens and carpels alone.  His enormous compilation was finally condensed in hundreds of pages of discussion complemented with charts that compare the genera he groups in different Sections of a Family.  
Adanson seems to have been a “splitter” regarding genera.  In his Section 10, the Bidenentes, Adanson lists 18 genera, 12 of which he named newly in the chart (see the list in the Appendix).  Of those 12, only two are currently accepted, Borrichia and Liabum, the rest being considered synonymous to other (mostly Linnaean) genera.  His Borrichia was populated with a single species, illustrated in 1732 by Dillenius in Tab 38.  (Recall that Linnaeus cites the previous illustration, Tab 37, in his description of Silphium asteriscus – Dillenius wasn’t far off base)

Tab 38, from Dillenius, the illustration Adanson cites for Borrichia

The species assigned to Adanson’s genus, however, do not include include his name in the authority; all are credited to De Condolle who described them in his 1838 Prodromus. Adanson didn’t employ the new Linnaean system of trivial names.

Finally, investigating the taxonomic history of Chrysogonum is a slam dunk. Linnaeus included Chrysogonum virginianum in the 1753 edition of Species Plantarum,  The taxonomy hasn’t really been questioned, for 220 years – eleven score.

I noted these plants have been grouped in the Subtribe Engelmanniinae, erected in 1977 by Steussy. Unfortunately, until I’m able to locate a copy of the text (The Biology and Chemistry of the Compositae, edited by Heywood, et al), the explanation for this hides out behind a paywall. It is interesting Steussy elected to typify his subtribe with Nuttall’s monotypic genus Englemannia rather than follow precedent in using Silphium as the type genus. Hoping there is some reasoning included in that publication.

Thanks to Jerry Pitts, Box R Manager, and Toni Brannon, Regional Permits, for assistance in obtaining permits and access to the Box R WMA, Apalachicola, FL

Thanks to Ruby Roberts and Forest Supervisor Kelly Russell for permission to study and voucher plants in Apalachicola National Forest.

Thanks to Mark Kiser for permission to study and document plant life in Tate’s Hell State Forest

Adanson’s list of genera assigned to his Section 10 – Bidentes

  • Adanson genera accepted today:
    • Borrichia 3 accepted species   (Asteriscus of Dillenius Elt.t.38)
    • Liabum 37 accepted species
  • Adanson genera considered synonymous to others:
    • Bikera = Tetragonotheca L.
    • Eupatoriophalocron = Eclipta L.
    • Cargilla = Chrysogonum L.
    • Vosacan = Helianthus L.
    • Ridan = Verbesina L.
    • Ucacou = Synedrella Gaertn.
    • Tepion = Verbesina L.
    • Detris = Felicia Cass.
    • Seala = Pectis L.
  • Linnaeus genera in Adanson’s Bidentes:
    • Coreopsis (misspelled as Coropsis)
    • Sigesbecka
    • Zinnia
    • Bidens
    • Tagetes
    • Milleria


Linné, Carl von, 1707-1778, 1753.  Species plantarum : exhibentes plantas rite cognitas ad genera relatas, cum diferentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas  DOI:  Holding Institution:  NCSU Libraries  Vol 2:  Vol 1:

Linné, Carl von, 1707-1778 1754, Genera plantarum : eorumque characteres naturales secundum numerum, figuram, situm, et proportionem omnium fructificationis partium  Holmiæ (Stockholm), Impensis Laurentii Salvii, 1754  DOI: Holding Institution:  Missouri Botanical Garden, Peter H. Raven Library

Royen, Adrianus van, 1704-1779 , 1740.  Adriani van Royen … Florae leydensis prodromus :exhibens plantas quae in Horto academico Lugduno-Batavo aluntur.  DOI:  Holding Institution:  Missouri Botanical Garden, Peter H. Raven Library  (Linnaeus cites as Roy. Lugdb.)

Linné, Carl von, 1707-1778 , 1737.  Hortus Cliffortianus: plantas exhibens quas in hortis tam vivis quam siccis, Hartecampi in Hollandia, coluit … Georgius Clifford … reductis varietatibus ad species, speciebus ad genera, generibus… DOI:   Holding Institution:  Missouri Botanical Garden, Peter H. Raven Library

Gronovius, Johannes Fredericus, 1686-1762 and John Clayton, 1686-1773, 1743.  Flora virginica, exhibens plantas quas v.c. Johannes Clayton in Virginia observavit atque collegit. Easdem methodo sexuali disposuit, ad genera propria retulit, nominibus specificis insignivit, & minu…  DOI:  Holding Institution:  Harvard University Botany Libraries

Dillenius, Johann Jakob, 1732.   Elthamensis seu plantarum rariorum quas in horto suo Elthami in Cantio coluit Vir Ornatissimus et Praestantissimus Jacobus Sherard, M. D. Soc. Reg. et Coll. Med. Lond. Soc. Guilielmi P.M. Frater, delineationes et descriptiones quarum historia vel plane non, vel imperfecte a rei herbariae scriptoribus tradita fuit. / Auctore Jacobo Dillenio M. D. [vol. 1] Holding Institution: Real Jardín Botánico, Madrid, Biblioteca Digital, Permalink

Tournefort, Joseph Pitton de, 1656-1708, 1700.  Josephi Pitton Tournefort … Institutiones rei herbariæ.  DOI:  Holding Institution:  Missouri Botanical Garden, Peter H. Raven Library

Candolle, Augustin Pyramus de, 1778-1841 and Candolle, Alphonse de, 1806-1893, 1836.   Prodromus systematis naturalis regni vegetabilis, sive, Enumeratio contracta ordinum generum specierumque plantarum huc usque cognitarium, juxta methodi naturalis, normas digesta  DOI:  Holding Institution:  Missouri Botanical Garden, Peter H. Raven Library

Adanson, Michel, 1727-1806, 1763.  Familles des plantes.  DOI:  Holding Institution: Missouri Botanical Garden, Peter H. Raven Library
Conrad,  Jim    Seaside Oxeye, Post on Excerpts from Naturalist Newsletter.

Lisa S. Rowan, University of North Florida, 2014.  Effects of Asphondylia borrichiae, Simulated Herbivory, and Nutritional Status on Survival, Flowering, and Seed Viability in Sea Oxeye Daisy (Borrichia frutescens)

Biber, P., J. D. Caldwell, S. R. Caldwell, and M. Marenberg. 2013. Sea-oxeye Daisy, Borrichia frutescens, Propagation Guide. Center for Plant Restoration and Coastal Plant Research. Last accessed: December 12, 2013. 

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