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Manual de Plantas de Costa Rica

Main | Family List (MO) | Family List (INBio) | Cutting Edge
Draft Treatments | Guidelines | Checklist | Citing | Editors

The Cutting Edge

Volume XVI, Number 4, October 2009

News and Notes | Leaps and Bounds | Germane Literature | Season's Pick | Annotate your copy

GONE SOUTH.  Manual Rubiaceae contributor Charlotte Taylor (MO) journeyed to Costa Rica for a two-week stay in July, mainly for herbarium work at CR and INB, where she identified a staggering backlog of material.  In the process, she inevitably discovered numerous new country records, some of which have already come to our attention (see under “Leaps and Bounds”).  Charlotte is tying up loose ends for her Manual and Flora mesoamericana treatments, both in the final stages of preparation.  During the month of September, Manual aquatic families virtuoso Garrett Crow (NHA, retired) set up shop at INB, annotating specimens of Podostemaceae et al. on the one or two days per week he could spare from volunteering with his daughter, a Costa Rican resident who works at a church-related social services clinic in the El Carpio favela.  And finally, Michael Nee (NY), specialist in various families, most notably Cucurbitaceae and Solanaceae, was in Costa Rica during the second week of October, having been invited by the Museo Nacional to annotate their material of Solanaceae. Lynn Bohs (UT) is the Manual contributor for that family, but oh well, the more the merrier.  Under the circumstances, Mike had time for only a few minutes at INB.

SOME DATA ON DATUMS.  Historically, plant collectors have not been overly concerned with pinpoint accuracy in expressing their locality data (and in some cases have been intentionally vague).  Count us among these heedless hordes. For most of our careers, we’ve simply estimated our position to the best of our ability from topographic maps, and sometimes still stubbornly continue to do so, even while toting GPS units in our packs.  Nor have we ever made any effort to indicate the precise position of each specimen collected, rather, in most cases, simply a centralized position for the entire day’s harvest.  In compiling our Gazetteer of Costa Rican Plant-Collecting Localities, all of the coordinates and elevations were taken directly from topo maps. Now, it will come as little surprise to most modern workers that maps and GPS units inevitably yield slightly different values for the same site.  This is because they are based on different “datums,” a datum being defined more or less as an idealized mathematical model of the earth’s shape tailored for a particular region.  Costa Rican topo maps are based on the Ocotepeque Datum, while GPS units (which must work everywhere in the world) employ the World Geodetic System 1984 Datum (WGS84).  In practice, this means that the geographic coordinates on Costa Rican topo maps differ by about 260 m from those provided by GPS units for the same positions.  Again, discrepancies of this magnitude are of little importance to our work, but anyone desperate for a resolution to this problem should consult the following highly pertinent and authoritative article, which is apparently available only on the Internet:


This is the Rosetta stone, providing both low- and high-tech solutions, the latter entailing detailed instructions on programming your GPS to “speak Ocotepequean” (specifically intended for Trimble brand GPS units).  Our predictably Luddite initial reaction to this?  Hey, if the topo map/GPS discrepancy is to be resolved by programming the GPS unit to “speak Ocotepequean,” we’re back to Square One:  let’s just toss those expensive electronic gadgets and go back to using the maps!  After all, Ocotepequean is their mother tongue.  This comes as a revelation to us, as our assumption had always been that GPS units are more accurate than topo maps, at least where latitude and longitude are concerned.  But it seems that, in theory, the reverse may be true:  Costa Rican topo maps are based on a specially selected regional datum, GPS units on a generalized global datum. The problem with using maps (accounting for the “in theory” caveat) is that it is virtually impossible to plot one’s position with pinpoint accuracy. GPS units make this possible, so programming the GPS to “speak Ocotopequean” combines the best attributes of both systems.  Elevation is “a tougher problem,” partly because “GPS technology is inherently worse at judging altitude than latitude or longitude,” while contour lines on topo maps “are only as good as the surveying that defined them.”  Thus, any apparent precision achieved by the suggested altitudinal conversions “is usually meaningless” (so GPS units offer no clear advantage here).  In any case, the subject of elevation is addressed.  This business of datums, of which we had been wholly ignorant, was brought to our attention by Mario Blanco (FLAS/JBL), to whom we are also indebted for the Rosetta-stone link.

ONLY IN COSTA RICA.  We have just learned that Alfio Piva, INBio’s long-time Executive Director, has accepted an invitation to run as vice president of Costa Rica on a ticket that is “almost certain to win.”  While this could mean better days for INBio somewhere down the line, the immediate future for the insitution is uncertain, as Don Alfio will be leaving his post there. Rodrigo Gámez, one of INBio’s founding fathers, will step in as interim director while a replacement is sought

CERRO RAYOS SAVANNA BURSTING IN FLOWER.  We always stop at Cerro Rayos, along the Puriscal–San Pablo back route to Orotina, but until now most of us had only collected very briefly and right along the road.  The site, perceptibly drier than the surrounding region, is chock full of species more typical of the Guanacaste lowlands, most notably Curatella americana L. (Dilleniaceae).  Perhaps because of this year’s unusually dry rainy season, the flowering that is going on right now caught Manual co-PI Barry Hammel’s eye on a recent pass, inspiring a day trip (in the company of wife and INB herbarium assistant Isabel Pérez and INB collector and herbarium assistant Daniel Santamaría) specifically targeting the area.  Supplementing numerous in-country distribution records for families already published in the Manual (see under “Leaps and Bounds”) are a few similar records (requiring us to tweak distribution statements) for families not yet published:  Ipomoea capillacea (Kunth) G. Don (Convolvulaceae; Hammel et al. 25427), Mimosa somnians Humb. & Bonpl. ex Willd. (Fabaceae/Mimosoideae; Hammel & Pérez 25364), Polygala tenella Willd. (Polygalaceae; Hammel et al. 25420), Schwenckia americana L. (Solanaceae; Hammel et al. 25418), and Turnera pumilea L. (Turneraceae; Hammel & Pérez 25361).  Those are spp. that we know by sight; the bulk of the material has not been studied (and is not even out of the drier!).  These savannas are rare and beautiful places, and for botanists used to the frustrations of dense, tall forests, a real pleasure to explore.

VOLCÁN IRAZÚ:  UNDERFOOT BUT OVERLOOKED.  The recent discovery of a new family for Costa Rica (see Fumariaceae, under “Leaps and Bounds”) reminded us that Volcán Irazú, despite its proximity to the Valle Central, has lately been somewhat ignored by local botanists (at least we have a good excuse:  so much work to be done in more pristine areas!). Responding to this wake-up call, just a few hours of serendipitous roadside collecting on the slopes of Irazú netted us several rarely found spp., requiring some slight modifications of impending Manual family treatments. Among these:  the European adventive Anagallis arvensis L. (Primulaceae; Hammel et al. 25343), apparently known only from this area in Costa Rica; Ipomoea dumetorum Willd. ex Roem. & Schult. (Convolvulaceae; Hammel et al. 25336), otherwise known from Costa Rica only by a few collections from the Cerro de La Muerte region; and Polycarpon tetraphyllum (L.) L. (Caryophyllaceae; Hammel et al. 25344), another Old World ruderal, first collected by Jorge Gómez-Laurito (USJ) nearly 30 years ago and not again, apparently, until now.


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