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Evidence of Hybridism.
In almost every locality where a considerable number of individuals of two or more jordanons of Celmisia occupy the same or contiguous habitats, hybrid individuals and less commonly hybrid swarms are encountered. Field evidence alone has been relied on in determining the parentage of each cross, but usually this has been such as to eliminate all doubt as to the correctness of the identifications. As a safeguard, however, no record has been entered save where my field companion Mr J. H. Hadfield and I have independently arrived at the same conclusion.
The usual field evidence sought for in each instance has been:—
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1. Are the supposed parental forms growing in the neighbourhood of the supposed hybrid?
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2. Are the characters of the reputed hybrid intermediate between those of the parental forms?
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3. Are there in the neighbourhood other species or varieties from which the hybrid characters could have been derived?
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4. Are there in the neighbourhood other plants so similar as to constitute a distinct jordanon; is the plant a distinct isolated individual; or is it one of a series of forms intermediate between species present in the area?
The following cases are worthy of record by way of illustration:
1. It was suggested to me that Celmisia insignis might prove to be a hybrid between C. Lyallii and C. longifolia. The fact that C. Lyallii has nowhere been seen in Marlborough and that C. longifolia has nowhere been gathered in the area of distribution makes it clear that the suggested hybrid origin is incorrect. The further fact that numerous similar individuals abound proves the existence of a valid jordanon.
2. Celmisia cordatifolia var. Brockettii was queried as a possible cross between C. cordatifolia and C. spectabilis. In this case the latter plant does grow nearby, but the former does not, being restricted to the Sounds-Nelson Botanical District. All plants observed were as nearly identical as plants ever are in nature, and they were unreservedly given varietal rank.
3. During a whole day spent on the eastern slopes of the Red Hills the only species of Celmisia observed were C. spectabilis var. albomarginata and C. gracilenta. The discovery of a solitary individual combining the slender growth form and scape of the former with the more distinctive characters of the latter left small room for doubt as to its hybrid origin.
4. On the slopes of Mount Patriarch, at a height of 4000ft. and more, there exists a huge swarm of individual plants all attributable to C. spectabilis or its varieties, yet no two alike. Careful observation revealed the fact that three distinct jordanons of C. spectabilis which occur in Marlborough had here met. The result was a very complex swarm of hybrids, the influence of each parental variety being very evident.