162 CaCtus and suCCulent Journal

odd oPuNtias QUIABENTIA AND BRASILIOPUNTIA

RooT GoRELICK

The cactus subfamily Opuntioideae contains every-thing from pedestrian prickly pears and chollas to the more peculiar Pterocactus, Puna, and Pereskiop-

sis. In eastern Brazil we saw two of the more bizarre gen-era: Quiabentia and the eponymous Brasiliopuntia.

Quiabentia is the sister genus to Pereskiopsis, belong-ing in the clade containing North American cylindrical stemmed members of the subfamily1,2. Q. verticillata grows at least 2000 km from Q. zehntneri, the former in west-ern Paraguay and nearby portions of Bolivia and Argenti-na, the latter endemic to Bahía and Minas Gerais, Brazil3.

Q. verticillata is a large tree, while the Brazil-ian Q. zehntneri is a small shrub to two or three meters tall, resembling its close relative Perski-opsis. While we only saw Q. zehntneri on lime-stone outcrops, apparently it can also be found under other edaphic conditions.

The monotypic genus Brasiliopuntia is the sister genus to Tacinga, but not the vegetatively similar North American genus Nopalea2. Brasil-iopuntia brasiliensis has bee-pollinated, bowl-shaped flowers with yellow or greenish-yellow petals, quite unlike the hummingbird-pollinated flowers of Nopalea and Tacinga. Growing at the

periphery of dense forests, it starts off with a fast growing cylindrical trunk from which originate flat pads and occassional cylindrical branches. The trunk bolts vertically toward the canopy to escape the shade of its non-cactus compatriots, a race that may make Brasiliopuntia, at 20–25 m, the tallest freestanding cactus3. Neverthless, plants growing even a few meters inside of a forest are notoriously difficult to find, even with their vibrant red fruits.

RefeRences

1 Stuppy W. 2002. Seed characters in the generic classifica-tion of the Opuntiodeae (Cactaceae). pp 25–58 In Hunt DR, Taylor NP, editors. Studies in the Opuntioideae (Cactaceae). David Hunt, Sherborne. 2 Griffith MP, Porter JM. 2009. Phylogeny of Opuntioideae (Cactaceae). International Journal of Plant Sciences 170: 107–116. Also see Wallace RS, Dickie SL. 2002. Systematic implications of chloroplast DNA sequence variation in subfam. Opuntiodeae (Cactaceae). pp 9–24 In Hunt DR, Taylor NP, editors. Studies in the Opuntioideae (Cactaceae). David Hunt, Sherborne. 3 Taylor NP, Zappi DC. 2004. Cacti of eastern Brazil. Kew, Surrey.

K A 2-meter-tall specimen of Quiabentia zehntneri grows at the transition between sparse woodland and bare bambuí limestone. Leaves are about to abscise, giving an overall yellow color.

I The crown of Brasiliopuntia brasiliensis at forest edge (note spider for scale) sits atop a stem only 7–8 meters tall. Long, hard spines grow as cladodes age. Glochids are most noticeable on flowers and fruits.