Phoebanthus – Floating Rays of Sunshine

In  A Flora of North America (1842), John Torrey and Asa Gray described a new genus by embellishing Helianthus with a diminutive suffix to coin Helianthella, delimited to encompass Nuttall’s 1834 Western US native, Helianthus uniflora and four other sunflower outcasts.  Among those five plants, two were newly described Florida species, Helianthella grandiflora and Helianthella tenuifolia. Even then, it was obvious the Florida species comprised a distinctive pair, the larger of the two being H. grandiflora, described from specimens collected in East Florida by Dr. Leavenworth and by Dr. Burrows.  The other description, that of Helianthella tenuifolia, cited one source “Sand hills, Middle Florida, Dr. Chapman! “

Dr. Alvan Wentworth Chapman included both Torrey & Gray species in his Flora of the Southeastern United States…, in which we can read his own description for our local (and endemic) Helianthella tenuifolia

“Hirsute; stem simple, or corymbose at the summit.; leaves narrow-linear, entire, the lower ones opposite or whorled; the upper alternate; scales of the involucre lanceolate-subulate, spreading; pappus of 2-4 acute awns.  Dry sandy pine barrens.  West Florida.  June and July, Stem 1’-2’ high.  Rays 1’-11/2” long.”

We can learn a bit from Chapman by translating his technical description to contemporary street language: 

“The plant is covered with short hairs, and grows by single 1-2 foot stems that may branch toward the top.  The leaves are narrowly linear, with smooth edges.  Floral heads are wrapped in bracts (the involucre) that taper to extended tips, pointing outward.  The ray petals are about 1.5 inches long.  You’ll find 2-4 sharp teeth at the top of the 1-seeded fruit (called achenes, or cypcelae) where other Composites might have a feathery pappus.  The plants grow in the understory of pine flatwoods in the Florida Panhandle, flowering in June and July.”

Nearly 75 years later, in 1916, Sidney F. Blake, a botanist with the U.S. Department of Agriculture, determined the two Florida species should be segregated to their own genus, describing the taxon we know today as Phoebanthus. You can read some of his reasoning below, but the amusing thing is that with this name he manages to devise another way to say “sunflower”, since Phoebus is an epithet for Apollo, representing brightness in his role as one of the sun gods. The cleverness of this new name came after Chapman’s time. He passed away in Apalachicola in 1899, and never knew these plants by names we use for them today.  But as living plants, he certainly knew Phoebanthus tenuifolius better than any botanist who ever dealt with its the taxonomy. 

For those interested in native plants, these are virgate floral sirens, calling to the passerby as elegant yellow flower-heads floating in open understory of drier pine flat woods (areas with soils that are not frequently inundated.)  That “from-a-distance” look is intensified by the remarkably, almost impossibly slender substance to stem and leaves, which allows the plant itself to meld and sway into its surrounds.  They are, to me, disembodied heads, hovering in the understory.

Veering into technical descriptions a bit, Phoebanthus tenuifolius stems are slim, stiff and wirey, ranging from a foot to three feet tall, often appearing as solitary specimens, but sometimes developing in small, loose colonies.  Larger plants often will bear 2-3 branches toward the top, each terminating in a single flower head.  The reddish (often very red) stems are populated by short, stiff hairs that are irregularly appressed to the surface and invariably point apically.  Leaves are spaced evenly along the stem, very thin and stiff in character, standing out at at right angles, though a bit chaotically.  They are scabrous to the touch, covered with tapering geniculate, setose trichomes.  It’s hard to imagine how such little leaf surface can photosynthetically support this enterprise, much less how the long but thin stem can keep that huge flower head upright. Everything about these plants reeks of individualism.

Being Sunflower relatives, the large ray flowers are sterile, in fact they often fall away even while the disc flowers seem to remain relatively fresh. It’s a vanishing act that makes for a sudden change, as what was a striking horizontal flower head, from 2 to nearly 4” across, one that faced stalwartly upward, not exhibiting any heliotropic tendency, suddenly becomes a wand topped by a convex knob (head) of yellow disc flowers. Those disc flowers are persistent, each paired to one of an equal number of receptacular bracts, i.e. palea.  Blake was impressed by the prominent palea, which half-sheath disc florets their entire length, referring to them as “squamellae.”  The flower heads are encompassed by somewhat leafy involucral bracts, the green, hirsute tips of which splay outward. 

I see very little (beyond Craig Huegel’s website) as to using this plant in native gardens.  It’s suggested you grow them from seed, but both seed sources, as well as germination and establishment information are scarce.  We know aerial stems arise from curious white, fleshy and knobby underground stems established in sandy soils, but I haven’t discovered how long it takes for a seedling to reach flowering size, much less to set up housekeeping as a small colony.  Phebanthus tenuifolius is listed as Threatened in Florida, having a very narrow distribution.  Though locally abundant under the right circumstances, I have not encountered specimens growing outside managed and protected forests.


The Inside Story

As to specifics Torrey and Gray give for Helianthella tenuifoila

“stem slender, scabrous, simple, or branching at the summit; leaves very narrowly linear, 1nerved, very scabrous; scales of the involucre lanceolate-subulate, loose, hirsute, as long as the disk; rays 10-12; chaff oblong, 3-lobed, shorter than the corolla; achenia glabrous, short, quadrangular; the anterior and posterior angles strongest or somewhat margined, each produced at the summit into a stout, persistent chaffy tooth, the intermediate angles obscurely toothed — Leaves 2 inches or more in length, less than a line wide.  Heads not half the size of the preceding (i.e. Helianthella grandiflora)…  Disk- corolla short, glabrous; the proper tube very short and indurated.  Style bulbous at the base.  Summit of the atheneum obscurely coroniform, produced into a short somewhat lacerate tooth at the principal angles (the inner angle strongest), and very obscurely toothed at the intermediate angles.”

Sidney Blake, considered one of the 50 greatest living botanists of the mid-20th Century, contributed greatly to the systematics of Composites.  In his 1916 publication, we read his considerations in defining the new genus: 

“The two species of Phoebanthus (Phoebus, the sun, and anthos flower) form a small group very similar to Helianthus in habitat characters, but technically more closely allied to Helianthella.  From the former, Phaebanthus differs sufficiently in the numerous short, persistent squamellae united into a low denticulate crown, from the latter in habit and achenial characters, as also in range, the species of Helianthella being West American and Mexican, of Phoebanthus Floridan. 

Astonishingly, the 1842 Torrey & Gray description in The Flora of North America is more developed than what is reported in the new Flora of North America, a diagnosis that may get the prize for the briefest text in that growing compilation:

Phoebanthus tenuifolius (Torrey & A. Gray) S. F. Blake, Proc. Amer. Acad. Arts. 51: 520. 1916.

Pineland false sunflower

Helianthella tenuifolia Torrey & A. Gray, Fl. N. Amer. 2: 333. 1842

Perennials, 40–100+ cm (tubers 2–4 cm). Leaves all opposite, or opposite and alternate, or all alternate; blades linear-filiform, the larger 3–7 cm × 0.5–2 mm. Involucres campanulate to hemispheric, 10–12 × 10–15 mm. Paleae 7–8 × 1.5–2 mm (central lobes usually longer than lateral lobes). Phyllaries spreading. Ray laminae 20–40 mm. Disc florets 40+; corollas 4–5 mm. Cypselae 3.5–4 mm; pappi of 1–2, lacerate scales 0.2–2 mm plus 0–4 scales 0.2–0.3 mm. 2n = 34.

Flowering May–Sep. Sandhills, flatwoods; 10–30+ m; Ala., Fla.

Phoebanthus tenuifolius in known from southeastern Alabama and the panhandle of Florida.

You’ll note ISB as well as Flora of North America use “Pineland False Sunflower” as a common name for these plants. There’s something sad in that; like what makes a plant a “false” sunflower? This was never a pretense on the part of the plant. And isn’t that a name associated with Heliopsis (which means “looks like the sun”)? I wish we could call it Chapman’s Sunflower.

Flora – Main Index Page

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