Welcome to our feature plant profile. This will be a rotating item which will feature a different plant species every few months.
This season our focus is on Rebutias.
THE GENUS REBUTIA ( K. Schumann )
by R. D. Stephenson
This is a South American genus, erected by Karl Schumann and named in honour of a French wine grower and cactus dealer, Mr. P Rebut, in 1895. Its area of distribution is Bolivia and North-Western Argentina.
There are 51 taxa ±, which includes many synonyms, a legacy of the combination of several genera over a period of years, but due mainly to the revision of the genus by Edward F Anderson. He has included the genus Sulcorebutia, and reduced many species to sub-species and others to varieties.
The previous genera were Aylostera; Spegazziniana; Mediolobivia; Digitorebutia; Weingartia plus Sulcorebutia. Some of the species had been described more than once, due in part to some authors not including floral or seed characteristics in their descriptions. The lack of fast communications would have been another factor, in that one person could have made and published a description of a plant, but that description could not be circulated as quickly as today, and another description of the same plant/species made by someone else not knowing of the first.
However, some of the older generic names were used as Sub-genera in a previous hierarchical structure which is now redundant. A few of these older generic names are still in use by some nurseries and can be found on some seed lists.
Their general appearance is of a small plant with generally a green body. Some species have a dark brown/purplish epidermis and this only adds to their attraction; eg. Rebutia canigueralii (Syn. Weingartia caracarensis); Rebutia neocumingii (Syn. Weingartia neocumingii + 27 other Weingartia taxa, which have been included in this species).
The spination is variable, with woolly/hairy; pectinate; weak or bristly or small, but sharp. Many species have radials only, some with barely distinguishable centrals. Examples of woolly/hairy are R. minuscula; R. pseudodeminuta; R. spinosissima and R. wessneriana. Those with pectinate spines include Rebutia heliosa; R. marsoneri; R. aranacea; R. mentosa; R. steinmannii and R. canigueralii.
Spine colour is also variable, from white; brown; black; grayish-white; yellow-white. Some spines have a light or dark coloured base with a light/dark tip. As in most other genera, the variations are many.
Flowers also have a wide range of colours and shades; white; yellow; orange; red; mauve/ purple, with some blooms having a different colour in the throat. eg. Rebutia canigueralii-red flowers with a yellow throat. This is a very attractive flower.
Seed collection is fairly easy, as the capsules dehisce vertically. As the plants do not flower from the centre of the head, but from low down on the side, simply lick a teaspoon and place under the capsule and then remove the capsule. The seed, if any is spilled, should land in the spoon and stick. The genus comes fairly easily from seed and is a great way of expanding a collection.
These plants start flowering for me about mid-late October and are still flowering, albeit spasmodically, in late November. As there are new buds developing continuously, this process will go on for some time. They make a brilliant show in the greenhouse. It is difficult to choose one in particular, but probably Rebutia heliosa, because of its spination, flowers and clumping habit. Other favourites are R. marsoneri; R. minuscula; R. perplexa; R. pygmaea.
The main pests to watch for are the usual Mealy Bug and Root Mealy. I spray with Rogor and Confidor which I have to mix and an occasional burst with an aerosol pack of Folimat, which is the only way to obtain this product now. Always use mask, gloves and a respirator when using these sprays as they can be a long term poison. I have found that with a constant air flow over the plants due to open windows just about all the time, I do not have to use a fungicide. They are fed with Aquasol, about every three months and powdered cow manure when re-potting. During their growing season-spring/summer, I water at least once a week, tapering off towards the end of April. Through winter I water once a month and then only lightly.
A delightful genus, with great variety, both in body size and flowers, suitable for just about anyone who loves cacti.
© Copyright, R.D.Stephenson 18th November 2005
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