Natural Hybrids
Only one natural hybrid involving N. rigidifolia (with N. spectabilis) is known. This cross, which is only known from a single open rocky outcrop, may now outnumber N. rigidifolia at the type locality (as observed by Stewart McPherson in 2007). The hybrid differs from N. rigidifolia in having narrower pitchers with a strongly infundibular base and distinct hip around the middle. On the other hand, the pitchers of this hybrid are broader than those of N. spectabilis and have an expanded peristome, as well as a markedly shorter spur. Charles Clarke wrote of this cross: "Unlike N. ovata × N. spectabilis (from Gunung Pangulubao), this hybrid seems to combine the more attractive characteristics of both parent species, producing large, beautifully coloured pitchers".
The richly coloured lower pitchers of N. rigidifolia × N. spectabilis may superficially resemble those of N. macfarlanei. However, since that species is confined to Peninsular Malaysia, the two taxa are not easily confused.
Read more about this topic: Nepenthes Rigidifolia
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