. Bulletin of the British Museum (Natural History) Botany. H. kalmianum H. frondosum H. myrt ifol i um H. sphaerocarpum \ / / \ , H. apocyn,folium / H. microsepalum H. buck ley i H. prolificum H. nudiflorum H. cistifolium lorum — H. H. fasciculatum— H. brachyphyllum H. Iloydii H. limosum Fig. 4 Relationships in sect. 20. Myriandra, based on overall similarity (Stage I). Testing the diagram The earlier efforts to produce a classification of Hypericum (Choisy, 1821, 1824; Spach, 1836<3, b, c; Keller, 1893, 1925) resulted in schemes that were partly gradal, based on cor
. Bulletin of the British Museum (Natural History) Botany. H. kalmianum H. frondosum H. myrt ifol i um H. sphaerocarpum \ / / \ , H. apocyn,folium / H. microsepalum H. buck ley i H. prolificum H. nudiflorum H. cistifolium lorum — H. H. fasciculatum— H. brachyphyllum H. Iloydii H. limosum Fig. 4 Relationships in sect. 20. Myriandra, based on overall similarity (Stage I). Testing the diagram The earlier efforts to produce a classification of Hypericum (Choisy, 1821, 1824; Spach, 1836<3, b, c; Keller, 1893, 1925) resulted in schemes that were partly gradal, based on corresponding stages of evolutionary development, not on descent; and the general aim of the present studies has been to convert these gradal schemes into a cladal one. The lines on the evolutionary diagrams, therefore, all indicate trends, and it should be possible to indicate the points of corresponding character-change ( gradal points) along each line. Joining these points should produce concentric 'contour' curves or circles, depending on whether the primitive taxon is on the margin of the diagram or not (Robson, \911a: Fig. 1). If, however, (a) the character change has taken place independently more than once ( if the advanced character is polyphyletic), or (b) trend-reversals have occurred or (c) a trend has been misinterpreted, then two or more non-concentric circles will result. Thus Fig. 6 shows that in Hypericum there has been a trend from five styles to three or sometimes two; but in four sections (13, 15, 26, 30) there has been a reversion to five styles. Of course, as with hypotheses in general, the diagram can also be checked by adding data not used in its construction. In conclusion, it should be stated that, although the above method of constructing and testing evolutionary diagrams was developed independently, no part of it is wholly Please note that these images are extracted from scanned page images that may have been digitally enhanced fo
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