Gorteria diffusa subsp. calendulacea [Beetle Daisy]

[nfoto]

Rørslett, B. 2022. Gorteria diffusa subsp. calendulacea (DC.) Roessler. Asteraceae. Beetle Daisy. South-African flowers photographed in ultraviolet (UV) and visible light. LINK

 

Belonging to the highly variable Gorteria diffusa complex, known as Beetle Daisy, subsp. calendulacea is a small plant of the dry plains of Northern Cape province of South Africa. It is endemic for the province.

 

I photographed this subspecies at Skilpad National Park, Kamieskroon, Northern Cape. It grew in a mixed community of other members of the Asteraceae, many of which have strikingly orange flower heads.

 

Visible light image of the flower head,

 

 

 

The overall rendition in ultraviolet (UV) is dark with a dark greenish cast. The 'beetle' marks on the rays are  much less distinct in UV than seen with the nominal subsp. diffusa.

 

 

 

The UV appearance is strikingly different to that of subsp. diffusa, making one wonder where the two subspecies should belong to separate species.

 

All images on this page are copyright Birna Rørslett and may not be used without explicit permission of the author.

 

[Published 10 February, 2022]

[Andy Perrin]

Quote

 

The UV appearance is strikingly different to that of subsp. diffusa, making one wonder where the two subspecies should belong to separate species.

Hm. I would think there would need to be more than just different coloration to put them in different species? We allow quite a bit of variation in, say, dog and cat fur pattern and other attributes without saying they are different species, just different "breeds".

[nfoto]

They have been kept together or separated for more than 100 years ... so obviously difficult for the botanists to decide.

 

In the field, the two looked remarkably different not only under UV, as the foliage and flowers were rather different. However, as stated elsewhere, this complex centered around Gorteria diffusa is highly variable and sometimes it is better not to draw too many distinctions in a taxonomic sense.

[Fandyus]

I've been really enjoying the series of images you've been posting. Keep it up :)