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The identification of Ld coniferum and Ld xanthoconus

Several Atlassers have experienced problems with Leucadendron coniferum at Elses Peak just south of Fish Hoek and at Cape Hangklip. On flat sandy areas the plants resemble Ld cfrm and in rocky areas they look more like Leucadendron  xanthoconus, but in between they seem to be intermediate. What is the distinguishing difference(s) between the two species?

The Cape Peninsula Key in PAN 13 (pp 12-13) distinguishes the two species as follows. (Both have winged fruits of the section Alata, do not resprout (i.e. not Ld sgnm or Ld spis s) or have wide leaves (i.e. not Ld stro or Ld laur)):

X. Leaves hairless when mature, green. Cone reddish, bracts hairless on upper half Ld cfrm

X' Leaves hairy when mature, grey. Cone silver, hairy Ld xant

If there are flowers, or you can find old male flower heads, the following is the most important distinguishing character:

X. Male florets with stigma having a constriction below the tip Ld cfrm

X' Male florets with club-shaped stigma Ld xant

In Ion Williams' 1972 revision of Leucadendron the key goes as follows (starting at top of key):

1. Longest female stem leaves more than 60 mm (long) goto 18

18. Male abortive stigma constricted near the apex Ld cfrm

18' Male abortive stigma clavate (hoof-shaped) goto 19

19. Leaves somewhat falcate, sharply apiculate, often thinly adpressed pubescent Ld xant

19' Leaves not falcate (all other Ld species in Alata with leaves longer than 60 mm)

However, any experienced key-user will know never to stop at the key and to always read the descriptions of the species in order to ensure that no error has been made. Thus, in the text we read:

57. Leucadendron xanthoconus (Kuntze)Schum. [1893]

Ld xant is easily recognized by its narrow, somewhat falcate (curved like a sickle), apiculate (with a sharp tip) leaves which are clothed when young with a thinly adpressed (lying against) shining pubescence (soft downy hairs), and also by its distinctly bi-lobed pubescent cone bracts. Another useful character is the glabrous (hairless) perianth (petals) in both sexes. It differs from L. cfrm (L.)Meisn. which is a very much larger shrub with glabrous mature leaves, with larger fruiting heads and with broadly winged fruits.

70. Leucadendron coniferum (L.)Meisn. [1762]

Ld cfrm differs from all others in the shape of the male abortive stigma which is constricted below the apex.

Some measurements taken from the species accounts are as follows:

Illustrations from Ion Williams' 1972 revision are provided below. Unfortunately, the situation is not quite as obvious as the keys make out: the plants flagrantly disregard the key, having hairy leaves and hairless cones and silver cones and hairless leaves. On our advertised weekend trip on 25 April to Elses Peak we could not reach a consensus. We must assume that there are some hybrids, at least until we can obtain a male specimen during the flowering period (Aug-Sept).

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