RELAPSE AND RETROGRESSION. 85 



set up, producing the violet-blue or purple florets of 

 the salsify (Tragopogon porrifolius}, the deep blue 

 Sonchus alpinus, and the bright mauve succory, 

 Cichorium intybus. As a whole, however, the Ligu- 

 lates are characterised by what seems a primitive 

 golden yellow, only occasionally rising to orange-red 

 or primrose in a few hawkweeds. 



That this hypothetical explanation may be the 

 true one seems more probable when we examine the 

 somewhat similar case of the Stellatce. Here it seems 

 pretty clear that mere dwarfing of the flowers, by 

 throwing them back upon earlier types of insect 

 fertilisation, has a tendency to produce retrogression 

 in colour. Even in the more closely allied Dipsacece, 

 Valerianea, and Campanulacece, we see a step taken 

 in the same direction, for while the large-flowered 

 Campanulas and Scabiosas are bright blue, the smaller 

 flowered teasel (Dipsacus silvestris) is pale lilac, the 

 Valerianas are almost white, and the V aleriandlas 

 are often all but colourless. In the Stellatcz, the 

 same tendency is carried even further. As a whole, 

 these small creeping weeds of the temperate regions 

 form a divergent group of the tropical Rubiacecz (in- 

 cluding Cinc/wniacece), from which they are clearly 

 derived as a degraded or dwarfed sub-order. Their 

 square stems, their leaf-like interpetiolar stipules, and 

 their usually lessened number of corolla-lobes, all 

 point them out as derivative forms, not as survivals 

 from an early ancestral type. Now, the tropical 

 Rubiacecz have tubular blossoms with long throats, 

 and as a rule with five lobes to the corolla ; but many 

 of the Stellates have lost the tube and one corolla 

 lobe. Sherardia arvensis, which has departed least 



