The Prince of Wales Heath, Erica perspicua is a well-known and beautiful heather of the Kogelberg. It gets its name from the long-tubed hairy purple and white flowers that bear a resemblance to the Prince of Wales Feathers. Erica perspicua also grows in the Klein River Mountains but here it looks notably different from the Kogelberg plants and is called a different subspecies: Erica perspicua subsp. latifolia. To complicate matters there is a second very similar species, Erica macowanii. This too grows both in the Kogelberg and the Klein River Mountains, including at Phillipskop. In the Kogelberg, it is easily recognised as it has bright red and yellow flowers. In the Klein River Mountains though, it has purple and white flowers, an almost identical colour combination as many plants of Erica perspicua. The Klein River Mountain plants of Erica macowanii have also been attributed to a different subspecies: Erica macowanii subsp. lanceolata. The reasons for distinguishing the two species is a challenge left for the expert, but there are some helpful pointers for the botanist in the field.
Erica perspicua subsp. latifolia is a plant of the low-lying flats between Hermanus and Stanford. It is particularly common in the marshy areas around the R43 and can often be seen flowering amongst the taller growing Berzelia and Psoralea that line the road. It forms tall bushes, with many branches, flowering at all heights, and from a distance the flowers look completely white. This habit and habitat helps to distinguish it from the very similar Erica macowanii subsp. lanceolata. That species grows in seepage areas on the upper slopes of the Klein River Mountains, rarely below 300m altitude. It is invariably purple and white, often sparingly branched with fewer flowers clustered towards the tips of the branches.
The question is whether these differences are genuine species difference, or can just be attributed to variation in a population across the range of habitat and altitude. A closer examination of the two subspecies shows that they share many features in common but there are some differences which assist in separating them. Whether these characters hold consistently (the following observations were based on plants from only one population of each) is still to be established. It also brings into question whether they should be attributed to the parent species in question. Is there more in common between these two subspecies than either of them with their supposed Kogelberg relatives? (All the following observations apply to the Klein River Mountain subspecies, not the species as a whole.)
Apart from overall habit, the two subspecies differ slightly from each other in leaf hairiness. Erica perspicua has slightly longer narrower leaves, though their ranges overlap considerably, with very short hairs (0.1-0.2mm) along the margins. Erica macowanii has leaves with notably longer hairs (0.2-0.5mm). A similar difference in the hairs can be seen on the stems as well but on the flowers the hairs are more or less the same length. Both species have similar calyces but the calyx lobes of Erica perspicua have broader membranous shoulders at the base which overlap the neighbouring ones (not notably broad or overlapping in Erica macowanii).
The corolla of the two subspecies differ in colour in that Erica perspicua, at least in the Klein River Mountains, is more frequently white with only fading to purple; Erica macowanii has a more strikingly contrasting two-tone corolla of purple and white (similar to plants of Erica perspicua in the Kogelberg). In general Erica macowanii has longer flowers than Erica perspicua, but as with the leaves there is considerable overlap. There is more difference in the shape of the corolla. Erica perspicua’s corolla bulges just below the apex, with a slight contraction before the lobes flare outwards, almost reflexing. The corolla in Erica macowanii flares more or less consistently from the midpoint to the lobes, without a bulge and contraction just below the apex. The lobes do not spread as much either. This is particularly notable in the older flowers, where they remain spreading in Erica perspicua but Erica macowanii return to pointing forwards.
Inside the flowers, the stamens of Erica perspicua and Erica macowanii reflect the shape of the corolla. The filaments of Erica perspicua bend almost at right angles just below the anthers; this is the same place as the bulge in the corolla of that species. Erica macowanii has a much shallower angle between the filaments and the anthers. The stigma, style and ovary of the two species do not differ notably except in size, which probably just reflects the same difference as in the corolla. However, the ovary of the two populations examined did differ in number of ovules. Both have 8 locules in the ovary but each locule of Erica perspicua has 3-4 rows of ovules, whereas Erica macowanii had 2-3 rows.
These are the differences that were observed with the material at hand. It is to be determined if when further material is examined, these differences are consistent. Furthermore, closer comparison with the Kogelberg subspecies would be helpful to determine if the characters are consistent with the parent species. What is certain is that there are two different taxa in the Klein River Mountains, which inhabit similar but different habitats in terms of altitude and surrounding vegetation. The correct names that should be applied to these taxa is still open to debate and requires a much more in depth study than has been provided here. In the meantime both could be considered impostors to the true Prince of Wales Heath.
[Those who want to read about the original descriptions of the subspecies can find the relevant article here: https://abcjournal.org/index.php/abc/article/view/388]