Flora of Georgia and surrounding states
Granite Outcrop Plants

Gratiola amphiantha D. Estes & R.L. Small 2008, pool sprite, snorklewort

Many years ago (back in the 1980's), I first met Linda Chafin on a Georgia Botanical Society field trip to Camp Meeting Rock in Heard County near Franklin. I recall hearing her exclaim "it's a scroph!" as she laid on her stomach examining this tiny flower. I knew right away she knew her stuff. She's now the Conservation Botanist at the State Botanical Garden of Georgia  and author of Field Guide to the Rare Plants of Georgia. The only problem now is that the Scrophulariaceae has been totally dismembered and this plant is now in the Plantaginacae.

Taxonomy
A recent excellent study by my friend Dwayne Estes using both morphology and genetics determined that this plant is so closely related to Gratiola that he moved it there. This means it had to be renamed from the former Amphianthus pusillus Torrey which most references (both state and federal) still use.

As luck would have it, there already was a Gratiola pusillus, so that name was not available, so Dwayne took the old genus and turned it into the epithet, matching the Latin case. I've always liked the name amphianthus and am secretly happy for his choice.

Synonym
Amphianthus pusillus Torrey 1837

Etymology
Gratiola is derived from the Latin word gratia, agreeableness, charm; grace; favor, goodwill, kindness; popularity, esteem, credit; presumably from the lovely, if small, flowers.

The epithet derives from the Greek word ἀμϕι amphi, on both sides, via amphibious, because of its living "on both sides" of the water.

The common name pool sprite comes from its habit of living in vernal pools and being very small or sprite-like. Snorklewort comes from the long stem that grows from the basal rosette to the two floating leaves which resembles a snorkle. The name "little amphianthus" is disingenuous as a silly translation of the scientific name that shows up on the USDA PLANTS database and Kartesz checklist. Pool sprite and snorkelwort are true "common" names that people actually use. 

Status
Federally listed as threatened wherever found.
State of Georgia listed as threatened.
NatureServe status is G2 - Imperiled.

Distribution & Habitat
The Biota of North America has a county-level distribution map.
The UNC Atlas has a county-level distribution map.

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Snorkelwort is uniquely adapted for life in the vernal pools of hard crystalline rock outcrops of the Piedmont. These pools all share a 2+ inch nearly vertical rim that gives them the ability to hold water for an extended period after rains. 

This very small (~1 square yard) pool supports a small population on the Saint Mary's outcrop of the Ropes Creek metabasalt on the southeastern flank of Kennesaw Mountain near my home that I have been monitoring for three decades.

The summit of Arabia Mountain has numerous solution pits, including one quite large one with an area of about 500 square feet. This pool is home to thousands of snorklewort (along with the also federally listed black-spored quillwort, Isoetes melanospora Engelmann 1877). 

Unlike the far more common elf-orpine, snorklewort is only found in some 44 locations in the Piedmont of Alabama, Georgia and South Carolina. The bulk of the locations are in 17 Georgia counties

Description
Pool sprite is a winter annual, so seeds germinate in the late fall as early as late September. They grow into a basal rosette of leaves (see November 29, 2011 blog) in the thin mix of organic and inorganic material at the base of the pools. These flat leaves are opposite, linear and sharply pointed with bases as broad as the leaf (~1mm) that tightly clasp the tiny stem. In most rosettes, the upper two whorls of leaves grow much longer than the lower ones and make the plant appear to have only four leaves. Look carefully underneath and there is usually at least one more whorl of much smaller leaves. 

Since this remarkable plant lives in a very fickle habitat where conditions can change dramatically in just a day or so, it has developed several strategies for survival.

Here, in the St. Mary's outcrop pool in November of 2005 the plants are germinating with tiny leaves. I'm having some difficulty interpreting exactly what I'm seeing here but this is my best guess. These seem to be cotyledonary leaves (seed leaves) that have grown much larger as the roots of the tiny plant reach into the organic mix for nutrients. If my guess is right, these will develop into the pair of floating leaves at the end of the "snorkel", above the basal rosette that apparently will develop later. This does not happen every year and I'm guessing that it is something the plant does in response to the water level. What triggers that growth response is a total mystery to me.

 When water levels are adequate, a stem grows out of the rosette with the buds of two leaves which form floating on the surface of the water in the pool to hold a single flower in the air for pollination by tiny insects. The floating leaves can develop in November, and the flower opens in April. This is what gives it the name "snorkelwort" as this is what the long stem serves as from the underwater basal rosette. 

In the event that water dries up during flowering time, this plant has the ability for form a cleistogamous flower in the basal rosette that doesn't depend on pollination to produce seed so it can propagate the species even in a very dry year. Being an annual, it doesn't have to deal with the heat of summer as the plant has completely withered and the only thing that remains are the tiny seeds in the thin mix at the base of the pool that can withstand the intense heat these rocks can reach in the scorching Southern summers. It's entire life span is about half a year.

On March 20, 2013 atop Arabia Mountain, the crop of snorklewort was something to behold, by far the most I'd ever seen there (see bottom photo). With this abundance, I found a spot with a large number of plants and teased one out of the organic muck to examine its structure, and this photo is the result. Now, before anyone gets apoplectic about me pulling up an endangered species, when I finished examining the little plant I carefully planted it back into the muck.

What surprised me the most was the rather robust stem between the many flared out roots and the whorl of leaves. This is not visible in the layer of muck. The roots, while abundant, are shorter than I was expecting as the organic muck just doesn't seem to have that much in the way of plant macronutrients.

This little investigation served to impress me even more with this plant and its incredibly effective adaptation to this harsh environment.