We encountered this species in Bolivia at roadside in secondary, disturbed habitat bordering cultivated fields in an area that was very arid and hot. Dead cayman nearby added to the ambiance.

Suffrutescent herb to 1 m, extremely abundant, corollas mostly purple but some plants producing flowers nearly white in color; plants formerly ascribed to Ruellia coerulea have be synonymized with Ruellia simplex, but this is the wild type and it is SO very different from Ruellia simplex.

Wild collected, Bolivia, Tripp #6020 w/ Luján, and Clark (COLO); Photos by Manuel Luján; Blog post by Dina Clark

For starters, I will refer you to Ruellia “La Tranca” Numero Uno, aka Ruellia sp. nov., Tripp et al. 5971 & 5977. Why? Because Tripp et al. 5979 represents Ruellia sp. nov. 2, La Tranca Dos.

We thank you, Bolivia, for your most appropriately placed roadblocks on Earth.

This species was collected on a day that we were not planning on spending in the greater Caranavi area, but La Tranca kept us local for the next 8 hrs. We decided to head up a dirt track (a very dusty, dirt track) towards the small community of Bolinda. Along the way, we encountered this species, carpeting the steep, nearly vertical slope that comprised the roadside. I had guessed at the time that it must have been related to R. menthoides, or R. terminale. One massive RAD sequencing dataset later, I was partially correct…perhaps. This species, labeled as ‘sp48_Caranavi’ in the photograph of the clade shown here, is strongly resolved within the clade that contains R. menthoides and R. terminale, but it’s position therein is not yet well-understood (note the mere 27% bootstrap support…Felsenstein, you would be not be happy).

Some time has passed, and I am convinced this species is new to science. And that it is somehow, someway, ultimately related to R. menthoides, R. terminale, and a pile of other stuff, as you will appreciated.

Wild collected, Bolivia, E. Tripp #5979 w/ Manuel Luján & Dina Clark (COLO); Photos by Erin Tripp

Stymied by Ruellia taxonomy? Be confused no more! In this case, all thanks should be directed to Cecilia Ezcurra, an Argentian botanist I have never had the fortune of meeting. There are two people on this planet that more or less made my entire dissertation possible through their prior labor on Ruellia taxonomy: Cecilia is one, and Tom Daniel (California Academy of Sciences) is the other. I owe both so much gratitude so here it is – thanks to you both!

In 1989, Cecilia published a paper entitled “Ruellia sanguinea (Acanthaceae) y especies relacionadas en Argentina, Uruguay y sur de Brasil”. In this most welcomed manuscript, she clarified morphological differences within an otherwise tricky lineage of species with exclusively red flowers that have centers of distribution in Bolivia, Argentina, and surrounding areas. These species ’clade up’ in all molecular analyses to date, which is somewhat unusual among red-flowered, bird-adapted species of Ruellia (generally, the closest phylogenetic neighborhood of any given red-flowered species involves species with purple, yellow, or white flowers, but here seems to be a whole lineage of: red red red)Ruellia sanguinea grows in moist forests at mid elevations (1700 m or so), ranging from northern Argentina to Bolivia. Look for it by it’s blood red flowers. Below, I have modified and added to Cecilia’s original key from 1989. My thanks also go to Dieter Wasshausen (retired, Smithsonian), who worked very long and hard to produce the Acanthaceae treatment of Bolivia, as well as my colleague Alexander Schmidt Lebuhn (CSIRO), for helping make sense of this entire complex, which really needs a formal name.

Working key to Clade Red Red Red, which includes:

1. angustiflora: Argentina, Brazil, Paraguay, Uruguay
2. brevifolia: everywhere
3. gracilis: Bolivia
4. longipedunculata: Bolivia & Argentina
5. pearcei: Bolivia, Peru
6. ruiziana: Bolivia, Peru
7. sanguinea: Bolivia & Argentina
8. saccata: Bolivia, saccate corollas

1. Corollas distinctly pink……………………………………………………………………………………. Ruellia ruiziana
2. Corollas distinctly red…………………………………………………………………………………………………………….2
3. Flowers solitary, sessile or not, on very short peduncles, in axils of reduced apical leaves …………………….…………………………………………………………………………………………….….. Ruellia sanguinea
4. Flowers in cymose, multiflowered inflorescences…………………………………………………………….…..3
5. Leave linear……………………………………………………………………………..………………………Ruellia gracilis
6. Leaves otherwise………………………….………………………………………………………………………………………..4
7. Leaves always dark purple underneath……………………………………………………………..Ruellia pearcei
8. Leaves not dark purple underneath……………………………………………………………………………………….5
9. Corolla saccate……………………………………………………………………………………………….. Ruellia saccata
10. Corolla otherwise…………………………………………………………………………………………………………………..6
11. Calyx lobes < 10 mm long, linear….………………………………………………………………..Ruellia brevifolia
12. Calyx lobes > 10 mm long, lanceolate to oblong….…………………………………………………………………7
13. Stems markedly 4-sided, inflorescences generally equal to or shorter than the axillary leaves……………………………………………………………………………………………………………Ruellia angustiflora
14. Stems weakly 4-sided, inflorescences far exceeding the length of the axillary leaves…. ……………………………………………………………………………………………………………..Ruellia longipedunculata

Wild collected, Bolivia, E. Tripp #6021 w/ Manuel Luján & Dina Clark (COLO); Photos by Erin Tripp

We encountered this species in Bolivia (Sep 2016) in the foothills of the Andes where it was locally abundant in the understory of secondary forests. It is also known from central Brazil and areas of Ecuador and Peru. Distinguishing character is the strongly sigmoid – curved lower portion of the corolla. Flower color ranges from lavender to pink. In places, it grew symmetrically with Ruellia brevifolia, resulting in a possible hybrid between the two (Tripp 5971).

Wild collected, Bolivia, Erin Tripp #5975, 5984, 6002 w/ Manuel Luján, and Dina Clark (COLO); Photos by Manuel Luján; Blog post by Dina Clark