|Based on molecular systematics, species within the genus Ruellia have undergone evolutionary reversals from hummingbird to insect pollination.|
|Ethiopia Field Work, 6 April - 17 April 2010 by Erin Tripp|
6 April 2010
There are so many people here in Ethiopia.So many. Eighty million packed into 1.1 million square kilometers. It is a marked contrast from Namibia, which has only 2 million people in 825,000 square kilometers.
And this country is geographically vast, too. We spent the first day and a half just traveling to the initial collecting locality—the arid Borana region in the southern part of the country. We are here to collect several genera in Ruellieae (different from those in Namibia), although finding them in flower will depend upon early rains because we are here at the beginning of the reproductive season. We are sleeping in Negele, and today traveled about 100 km south of town on some truly awful roads. We found and collected Duosperma longicalyx along with several other Acanths much more common in the area including an Asystasia, Hypoestes, and Crossandra—this latter an attractive plant with all five of its petals comprising the lower lip (the upper lip is completely reduced). Another Acanth genus, very rare in far western Ethiopia, has independently evolved a similar morphology: Eremomastax. Crossandra is in the Acantheae lineage while Eremomastax is in Ruelllieae. The widespread and common Justicia flava, which we also collected today, appears to be an important food source for the local butterfly population.
I am here with Ensermu Kelbessa and, since we have an Addis Ababa University-owned Land Cruiser, a driver: Berhanu Yitbare. Berhanu also happens to be the head mechanic at the University: not a bad accompaniment. Ensermu completed the Acanth treatment for the Flora of Ethiopia and Eritrea a few years ago. Needless to say, he is also extremely handy.
Yesterday was botanically profitable. And long. Immediately following an early breakfast of foul, eggs, coffee, and bread, we departed Negele bound ESE towards the border where Ethiopia, Somali, and Kenya intersect (this whole region of Ethiopia is Somalia-occupied). At a site 40 km from town, we collected two common, here sympatric species of Ruellia (R. patula and R. prostrata), another Crossandra and Asystasia, a Lepiagathis, two Justicia, and a nice Barleria section Somalia. These were all growing within a small space of about 25 square meters—an Acanth rich area you might say.
We continued ca. 100 km south towards a handsome limestone outcrop to find two species high on my priority list: the restricted endemic Ruellia boranica (described by Ensermu), and one of two species of Satanocrater I hoped to see on this trip, S. ruspollii. We found both, but only the former was flowering. Ruellia boranica has bracts like a Petalidium (most distinctive within the genus Ruellia). Satanocrater ruspolii flowers gregariously, i.e., all plants come into flower at the same time. Just how frequently they flower, we do not know: either once every other year, or perhaps every fourth year. No one has yet studied it. Other genera in Ruellieae are also known to adopt this strategy, e.g., Acanthopale and many Strobilanthes. Just like in Namibia, these two species comprised the dominant plants of the landscape.
Although daylight was of concern (best not to travel at night in this particular geopolitical area), we punched it south for an additional, rough and rutted 100 km in hopes of rounding out the day with two other high-priority species. We had little time to explore upon arrival, but the added distance was worth it: we found the long, nocturnal, white-flowered Ruellia discifolia (still in bud due to our time of arrival) as well as the other species of Satanocrater: the bright orange-flowered S. paradoxa . It is paradoxical because of its peculiar corolla morphology: it is missing its fifth, ventral lobe (note the rudimentary red nub). Although down a lobe, it is still an impressive shrub. I had only a few minutes, but enough to observe an unidentified sunbird perching among the plants and visiting its flowers. Both species of Satanocrater are extremely pungent vegetatively, smelling something of an antiseptic-thyme elixir. Towards my lifelong goal of seeing every species of Ruellia alive, preferably in the wild, I added three new ones to the list…and camels, which are most amusing to watch while they eat. Their mouths move in perfect semi-circles—clockwise, then counterclockwise. Clockwise, then counterclockwise.
The return trip was 240 km, making it a total of almost 500 today on a special road. Following a coffee ceremony at breakfast, today was a repeat. We departed Negele northbound towards our next collecting site—the eastern part of Ethiopia circa Jima. The drive back to pavement took all day, including an 80 km rocky detour in which we unsuccessfully attempted to find the rare Ruellia bignoniiflora (another nocturnal white-flowered species, this one with tubes to 130 mm long!). Good thing our field vehicle is a seasoned beast. We did, however, happen upon Dyschorsite radicans as well as an Acanth with claims to one of the best generic names in all of botany: Crabbea.
The day after the drive away from Negele was also consumed by driving (this country takes a long time to move through): Negele to Shashememe was a full day, and Shashememe to Jima another. This morning we are in Bonga, east of Jima. We spent the better part of yesterday, on our drive from Jima, outside the car in fairly nice habitat, both of which were welcomed. But there were no stellar achievements in our botanical quest. In the first forest, we did manage to find three of the plants we are here searching for (Acanthopale aetho-germanica, Brillantaisia grotanellii, and Mellera lobulata), but all three were sterile. Like Satanocrater ruspollii, most (all?) species of Acanthopale are also gregarious: find one, find many, otherwise nothing. Unlike Satanocrater, however, Acanthopale is also monocarpic: it flowers once in its lifetime and then dies. Thus it is both gregarious and monocarpic. Lots of interesting reproductive strategies to be found in Ruellieae.
After reaching Bonga, we ventured on a second hike to a large and lovely waterfall (the species we are after prefer riparian corridors). We collected an as yet undescribed species of Barleria, but nothing else. Today we continue the search in surrounding areas. The troika is slow getting going this morning, under a four-hour hard rain, so I take the opportunity to write.
Yesterday was also disappointing botanically: we found what we were after, but everything again was without fruits and/or flowers. And like before, we traveled relatively short distances (< 200 km) over long hours because the roads were so abused. This time, the main route was actively under construction, laden with mudslides from Bongo clear to Mizan. We were in 4WD the entire time. Many of the other vehicles couldn’t pass the steep slopes and were thus forced to wait half a day until the mud dried for sufficient traction. After reaching Mizan, we had a few hours of daylight remaining and so departed on what was formerly a 4WD track last time Ensermu visited (a few years ago). It is now a bona fide road, mostly traveled by large flatbeds carrying Ethiopian tanks to the Sudanese border. What was once interesting habitat beyond the coffee farms and tea plantations that surround Mizan is no more. All the native vegetation has been destroyed, and with it, the Ruellieae we were after. The only good thing to come of the day was my finally convincing Berhanu to let me test out the old Land Cruiser. Culture contingency had it that he was certain females could not operate motor vehicles, let alone navigate such atrocious roads. I was determined to convince him otherwise.
Today was a completely different story. We departed Mizan north towards Teppi, and eventually landed in Metu after being caught an awesome tropical hailstorm. We collected Mellera lobulata , Brillantaisia grotanellii ), Phaulopsis imbricata, and the orange-spined Hygrophila schullii. All in flower. All in Ruellieae. The first two were growing in dense thickets on slopes that were near vertical (collecting them was not easy), but in beautiful primary forest that made the dirt and effort well worth it. We also picked up the striking (in more than one way) Acanthus polystachys (note bract and leaf spines), Rungia grandis, Monothecium glandulosum, two new Justicia, and a Dicliptera and Hypoestes. The Brillantaisia has something interesting going on morphologically in its flowers. Visible in the center of the flower are two sterile stamens or “staminodes” (the fertile stamens as well as the style are hidden in the upper hood). In general, staminodes do not serve reproductive function (although documented cases of their functioning as a “lever arm” in pollination are not exactly rare, cf. Lamiaceae). From a distance, they look like insect antennae. Perhaps this species is following the strategy of many orchids, which, to attract floral pollinators, have evolved morphologies to mimic sex-seeking insects?
There is a notable difference between the way people in one particular area value the landscape versus other areas. There is a very apparent respect for it here, which is lacking elsewhere. It seems to be a cultural difference rather than one more predictably based on population densities.
Yesterday we pointed the truck back in the direction of Addis Ababa. Ensermu has a talk to prepare for the upcoming AETFAT (Association for the Taxonomic Study of the Flora of Tropical Africa) meetings in Madagascar next week, and I will make use of the time in University herbarium. We left Metu in the morning and made a 120 km westerly detour towards Gambella to search for an unlikely plant population alluded to earlier. The genus Eremomastax has been collected only twice in Ethiopia. First was the pre-WWII type collection, with very poor locality data but “somewhere in northeast Ethiopia.” The other was collected in the early 1970s, in riverine forest of the Gambella escarpment that, as we learned, no longer exists. The habitat has been totally devastated: formerly wet, tropical rainforest turned dusty, wasted farmland. When you remove the trees in most tropical biomes, already nutrient-poor soils bake and what little nutrition the forest once contained is forever removed with the aboveground biomass. Still, we tried. I made a long descent down an extremely steep slope with loose rock strewn about from construction of the road. At the bottom, there were small, persistent populations of Blepharis maderaspatensis and a new Ruellieae for the list, Dyschoriste nagchana, but no Eremomastax. I was not surprised—it was a long shot. But on the bright side, I found Mellera again, this population flowering abundantly; plants were an impressive three meters in height. The genus should perhaps be added to the list of true trees in the Acanthaceae, along with the New World Bravaisia and Trichanthera, both in Ruellieae. Mimulopsis, also in Ruellieae and native to Ethiopia, achieves heights of 6 meters.
The day ended better than I could have ever hoped for… botanically, but not in sense I have been writing about. Back in Metu, we drove another 120 km towards our only shot at accommodations for the night (albeit a slim shot): Bedele. In town, the Bedele Brewery has guest rooms, but Ensermu reports they are very difficult to get into, always requiring a formal, written invitation. Somehow we managed. After unloading the car and pressing plants, I had time for a brief run, enjoying the competition of numerous young, enthusiastic Ethiopian children. The night got better. I was stopped by a former student of Ensermu’s (after he saw our Land Cruiser with the University emblem), who graduated Addis Ababa with a degree in chemistry and now happens to be the senior production manager at the brewery. We joined him for beers, shiro, and good conversation in the executive tasting lounge. Ethiopian beers are brewed under the German purity law (Reinheitsgebot)—slightly weaker than your average American lager, but delicious. I go to bed happy.
Yesterday, we drove the remaining distance to Addis above a scenic landscape (something on the order of 70% of Ethiopia is above 2,000 m elevation) and beneath abundant rainbows. The Acanthaceae species diversity we collected in Ethiopia is not as large as what was collected in Namibia, but the generic diversity here is greater. I walk away having seen and studied ten (of 11 total) Ruellieae genera that occur in Ethiopia, in their native habitats: Ruellia, Mellera, Brillantaisia, Satanocrater, Hygrophila, Duosperma, Dyschorsite, and, although sterile, Acanthopale and Mimulopsis (this last one collected just before my flight home, on the montane slopes surrounding Addis). I also learned a lot in the Addis herbarium, including a new use for the family: children’s entertainment. All in all, it was a successful trip.
Late this summer, Ensermu and his student Mekbib will come visit Rancho Santa Ana Botanic Garden. Mekbib will participate in a 10-day molecular systematics training workshop that is funded in part by another NSF grant, on Passifloraceae, which is based in part at RSABG. Ensermu, Lucinda, and I will collaborate on a project on palynological diversity of African Ruellieae. We will utilize samples collected on the Ethiopian and Namibian fieldtrips. After finishing the workshop, Mekbib will assist me with generating molecular sequence data for the project.It has been a most interesting and chaotic day. With the volcano erupting in Iceland two days ago and no reporter yet being able to pronounce its name, passengers have been stranded in Addis Ababa for 48 hours and counting (most flights from Africa terminate or transfer in Europe). These people are irate. My flight tonight was also cancelled (I was to transfer thru Amsterdam on KLM; Dutch airspace has been completely shut down). Because volcanic activity is increasing, and per the advice of KLM agents in town, I opted for the cancellation refund and sought another ticket. Nearly all alternatives were booked, but after a few phone calls in the Air Ethiopia office, I arranged to meet a travel agent in a private downtown office who, through powering his computer with a generator due to forced blackouts, got me the last seat on a Thai Air flight via Bangkok to LAX. I feel certain I am just about the only American who managed to make her way out of Addis tonight (and perhaps out of eastern Africa), which is most advantageous for me as I have other field commitments upon return to the US. Good thing LA is on the west coast.