Aloe canis S.Lane

Thiede, Joachim, Campbell-Barker, Theo Peter, Hargreaves, Bruce J., Smith, Gideon F. & Figueiredo, Estrela, 2020, Notes on three aloes of Malawi: Aloe cam's, A. lateritia, and A. suffulta (Asphodelaceae subfam. Alooideae), Bradleya 38, pp. 247-253 : 248-250

Aloe canis S.Lane

Aloe canis was discovered by one of us (TPC-B) in the 1970s on the northern slopes of the Senga Hills near Senga at the shore of Lake Malawi (Salima District, Central Province; Figure 1 : 1a). He collected two living plants that were at first thought to represent A. cameronii and observed two further plants on fairly level rocky ground somewhat inland from Domira Bay northwest of Senga ( Figure 1 : 1b), and a single further plant adjacent to a small, dry, seasonal riverbed on a slope of the Ntchisi Hills ( Figure 1 : 1c). The identity of plants observed at a distance with a pair of standard binoculars on the escarpment of the Angoni highlands remains uncertain ( Campbell-Barker, 2012: 21–22). Campbell-Barker cultivated the two living plants for many years in Blantyre (the largest city in Malawi; Figures 2 & 3). After his return to England, the plants came into the possession of Reverend Stewart Lane at Limbe, Malawi, who noted their distinctness and described the taxon as a new species A. canis (as “ A. canii ”), the epithet alluding to Campbell-Barker (Latin canis = dog; Lane, 2001; Lane et al., 2003).

When Lane left Malawi, one A. canis plant remained in the private garden of Ms Ruth Mthawanji, in Newlands, Blantyre, Malawi, and 50 seeds were distributed to a grower in South Africa which did not germinate and were likely of hybrid origin (G. Hayes, personal communication by e-mail on 16 June 2015 and on 17 January 2020 to one of us (JT)). The plant in the domestic garden of Mthawanji is still in cultivation (S. Lane, personal communication by e-mail on 10 January 2020 to one of us (GFS)), which was confirmed by Mthawanji (personal communication by e-mail on 16 January 2020 to one of us (GFS)). Mthawanji noted that the plant was indeed given to her by Reverend Lane some 20 years ago (i.e., ca. early-2000s) and that it has flowered regularly ( Figures 4 & 5 ) but has not produced fertile seed so far, likely because the species is self-sterile, as are most aloes and their generic kin. The plant does not produce suckers and it has not been possible to propagate it vegetatively. Lane (personal communication by e-mail on 16 January 2020 to one of us (GFS)) notes that Mthawanji’s propagation experience with A. canis is congruent with what he found, i.e., that the specimen he gave to Mthawanji, and likely the species in general, does not produce suckers and no or almost no viable seed, at least when not cross fertilised. His only success at propagating the species was by cutting the stem off, which resulted in the development of a few sprouts at the cut.

The stem height, given by Lane (2001) as up to 2.5m, should be corrected to about 1.5m ( Campbell-Barker, 2012: 25). In habitat, it appeared that some of the single-stemmed plants had wounds on the stem indicating that offsets may have been removed ( Campbell-Barker, 2012: 21).

The distribution area of A. canis in Malawi has been virtually denuded of all plants of Aloe ( Lane, 2004: 38) ; these were collected for various uses by the local inhabitants, especially as an ineffective treatment of AIDS by traditional healers (“singangas” in the local language; Campbell-Barker, 2012: 26). One of us (JT) explored the westernmost of the Senga Hills on 20 April 1991, but did not find any plants of Aloe ( Thiede, 1993: 31; Thiede & Campbell-Barker, 2015: 29). All attempts by several people to relocate the species failed and it is thought to now be extinct in the wild in Malawi ( Lane, 2004: 38–39). Recently what appears to be the same species has been found in Mozambique just across Lake Malawi from its [possibly] former location in Malawi (S. Lane, personal communication by e-mail on 10 January 2020 to one of us (GFS)).

Aloe canis was first considered to be a variant of A. cameronii , which it resembles, but it is generally larger, usually single-stemmed, and has denser rosettes with a few scattered maculations on both leaf surfaces near the leaf base ( Carter et al., 2011: 637); it might well have arisen as a spontaneous natural hybrid [or allopolyploid; JT] involving A. cameronii and a second species (Hayes, 2015). The type of the name Aloe canis , Lane 1, is recorded as deposited at Herb. MAL (holotype) and Herb. PRE (isotype). Neither of these specimens is available for examination online.

Figures

Figure 1. Distribution of three Aloe species rare in Malawi: 1) A. canis (yellow dots, a = Senga Hills; b = inland from Domira Bay; c = Ntchisi Hills; Central Region); 2) A. lateritia var. lateritia (blue dot = near Ipenza, two records; Northern Region); and 3) A. suffulta (red dot = Mwabvi Wildlife Reserve; Southern Region). Placements of the dots are partly approximations. The map insert shows the position of Malawi (red) in Africa (map: Wikimedia Commons 2019; insert map: mapsof.net 2015).

Figure 2. One of the two original plants of Aloe canis, flowering in cultivation in Blantyre, Malawi. Drawing: Pastor Theo Peter Campbell-Barker.

Figure 4. The specimen of Aloe canis that Ms Ruth Mthawanji received from Reverend Stewart Lane in the early-2000s photographed in Blantyre, Malawi, in 2015. Photograph: R. Mthawanji.

Figure 5. Panicle of the specimen of Aloe canis that Ms Ruth Mthawanji received from Reverend Stewart Lane photographed in Blantyre, Malawi, in 2019. Photograph: R. Mthawanji.