Crotalaria dura subsp. dura
Observation - Crotalaria dura subsp. dura - Southern Africa. Description: These images are added to help distinguish Crotalaria dura subsp. dura from C. globifera. Difficulty in doing so is exacerbated by the image in Elsa Pooley's A field guide to wildflowers (of) KwaZulu-Natal and the eastern region. The plant illustrated is
These images are added to illustrate Crotalaria dura subsp. dura and help distinguish it from C. globifera, which I have previously posted images of on iSpot. Difficulty in distinguishing the taxa is exacerbated by the image in Elsa Pooley's "A field guide to wildflowers (of) KwaZulu-Natal and the eastern region". The plant illustrated is not in fact Crotalaria dura and the description provided is mostly uninformative as to its distinctive features. All the images in this posting are of Crotalaria dura subsp. dura except one showing the keels of both taxa side by side.
Crotalaria dura subsp. dura is a taxon with a narrow distribution confined to the mainly Natal Group sandstone coastal escarpment of south-central KwaZulu-Natal, between about Dumisa/Highflats and Kranskop, although it also occurs on other geologies (the geology is complex in this area) and there are historical records from as far inland as Pietermaritzburg. It is somewhat misleadingly described by Polhill as occurring in the midlands of KZN, though the altitude range he provides (600-900 m asl) is too low for this midlands designation to be accurate. It is an indicator of good quality grassland though like many taxa it may persist for a time in the face of disturbance. Crotalaria globifera on the other hand has a wide distribution in eastern South Africa and is in my experience more prolific in slightly disturbed or coarse grassland. At some sites both species can be found in proximity.
Important differences between the two taxa are as follows.
1. Crotalaria dura subsp. dura has a prostrate, decumbent to decumbent-erect habit, whereas C. globifera has an erect habit.
2. Crotalaria dura subsp. dura has a keel petal that is rotund unlike the angled curvature and distally straight and elongate beak of C. globifera (thanks to Marianne le Roux for this, included in an article previously published in PlantLife)
3. Note also the often brown calyces seen in Crotalaria dura subsp. dura.