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Paul Hoxey

I continue the review of Peruvian Opuntioids by covering two genera and just two species, one native and one introduced.

TUNILLA

The name Tunilla was recently erected by David Hunt and James Iliff to cover a distinctive group of small joined Opuntia sometimes given the name Airampo.  The species are quite poorly understood and although quite a few  names have been described it is unclear how many good species there are. Fortunately the situation in Peru is less confused and only one species, Tunilla soehrensii, is named from the country which also happens to be the type of the genus.

Tunilla soehrensii

Tunilla soehrensii was originally described by Britton and Rose as Opuntia soehrensii, in honour of the German Botanist Prof. Johannes Söhrens. The type was collected by Dr Rose and his wife at Pampa de Arrieros inland from Arequipa in southern Peru. Sometimes the technical details in describing plants with terms such as “type” and “type location” can be confusing to non-botanists but they are of great value in understanding what a plant really is. In this case the accurately recorded type location allows us to return there today and examine the plants. For this species I have done just that and Figs. 1 and 2 show the species growing in the general area of Pampa de Arrieros and at Canon del Colca together with a sectioned flower (Fig. 3). It forms low and spreading clumps, offsetting at ground level with densely spined flattened pads. Plants often have a tatty appearance especially in the dry season when dehydrated. The pads suffer and become shriveled and often die. New pads are then quickly added after the rains.

Fig. 1

Fig 1. Tunilla soehrensii PH782.03. South of Pampa de Arrieros, Arequipa, Peru, 3310m.

Fig. 2

Fig 2. Tunilla soehrensii PH790.01. Canon del Colca, Arequipa, Peru, 3790m.

Fig. 3

Fig 3. Tunilla soehrensii PH790.01. Sectioned flower.

Tunilla soehrensii is commonly cultivated in the Canon del Colca region in southern Peru. Single pads are placed along the top of walls (Figs. 4-6) and happily grow on into plants. Within a few years quite large flowering sized clumps can form. The flowers are yellow with a green stigma and style. The stamens are sensitive to touch and curl up if a bee (or finger!) enters the flower.

Fig. 4

Fig. 4. Tunilla soehrensii PH787.01. Planted on a wall. Canon del Colca, Arequipa, 3440m.

Fig. 5

Fig. 5. Flower from the above plant.

Fig. 6

Fig. 6. Fruit from the above plant.

Perhaps the most interesting characters of the plant concern the fruits and seeds. I found some fruiting specimens in the Colca Canyon region and out of curiosity cut one open with the knife. I was surprised to find the seeds are under pressure and they pushed their way out of the fruit through the cut and the released seeds consumed perhaps twice the area they did in the closed fruit. This example showed unripe seeds that had not fully developed. A second surprise awaited when I opened a ripe fruit which contained seeds under pressure as before but now with a bright red pigment on the seeds (Fig. 7). The pigment is a very intense red and covers the seeds. On touching them the red pigment stains your fingers and is quite difficult to remove. The fruits are not juicy and the red pigment is restricted to the surface of the seeds. Historically the red pigment was used as a red dye for cloth but I do not know if it is still used for that purpose today.

Fig. 7

Fig. 7. Tunilla soehrensii PH788.01. Fruit with red seeds. Canon del Colca, Arequipa, 3440m.

I have found Tunilla soehrensii in many locations in the departments of Arequipa and Tacna in southern Peru. It is also known from Moquegua and its distribution extends into northern Chile. It is a plant of high altitude habitats between 2900 and 3800m.

CYLINDROPUNTIA

Cylindropuntia is a non-native genus to South America but one species has become quite widely distributed and naturalised through the actions of man. The genus is native to Mexico, the USA and some islands in the Caribbean. There are about 30 species. It is very easy to identify Cylindropuntia on account of the spines which are covered with a papery sheath. This can be observed in the species by gently tugging on the spine to release the papery sheath. (Danger! Do not use bare fingers! Ed.)

Cylindropuntia tunicata

Cylindropuntia tunicata was probably introduced into South America in pre-Colombian times for reasons not understood today. It is widespread but not particularity common. It tends to be encountered now and again in widely separated habitats. I have found the species in Chile as well as Peru. Some locations have had evidence of pre-Colombian occupation so it is likely the plant was introduced intentionally and cultivated. It is most often found along the coast in lomas habitats. Today these places are not populated but in the past they acted as oases which allowed people to live in the extremely arid environment along the Atacama Desert coast. I have also seen Cylindropuntia tunicata in the Río Apurímac, one of the inter-Andean valleys, well inland and some distance from the coast. Altitude is likely to place a factor in the distribution and I have not found Cylindropuntia tunicata above 2600m. (Figs. 8 and 9).

Fig. 8

Fig. 8. Cylindropuntia tunicata PH586.02. Growing on the Inca ruins at Lomas de Atiquipa, Arequipa, 1280m, Peru.

Fig. 9

Fig. 9. Cylindropuntia tunicata PH738.04. Puente Pasaje, Rio Apurimac, Cusco, Peru, 1150m. 

Cylindropuntia tunicata grows into a low bush with very spiny stems. I have not seen flowers or fruits in its Peruvian or Chilean habitats. Perhaps the majority of propagation is by vegetative means. The stems are not firmly attached and they can be broken off, perhaps by passing animals, and deposited elsewhere to form a new plant.                    

This article was originally published in Tephrocactus Study Group (the 'TSG Journal'), March 2012, Vol. 18, No. 1, pages 3-7, 11 and 15. © TSG and Paul Hoxey