The extent of the suspected hybrid colony appears to contradict this hypothesis, for if the increase in area has been due to the production of new plants, then there should be a significant proportion of F2 plants in the colony. However, the spreading and rooting habit of the Acaenas, which is an effective means of vegetative reproduction, suggests that the colony may have been entirely derived from a few original F1 plants. The low germination rate of seed from these presumed F1's and the low survival rate of seedlings suggests that F2 plants would find difficulty in establishing themselves under field conditions. In Fig. 4 it will be noted that the average hybrid index is displaced towards Acaena novae-zelandiae. A. possible explanation is that in the case of three characters scored in the more than two grades A. novae-zelandiae is probably overrepresented— ie, with growth habit inherent lack of vigour may reduce the number and length of laterals formed, and with cotyledon-length and first-leaf form, in respect of which the majority of seedlings resembled Acaena novae-zelandiae, A. novae-zelandiae dominance is probably a factor. The approximately normal curve formed by the hybrid indices does not suggest backcrossing to Acaena novaezelandiae. Lyall Bay-Seatoun Coast This area is a strip of coastline approximately three miles long partly within and partly outside the entrance to Wellington Harbour. It consists for the most part of a narrow coastal platform (averaging about 25 Yards wide) backed by steep hills. The platform came into being partly as a result of general uplift during the 1855 earthquake and the habitats so formed were later considerably modified by the construction of a coastal road in 1923. The soil consists mainly of rock fragments mixed with shingle and a small amount of sand. An extensive area of sand dunes formerly existed at Lyall Bay, but these were later levelled to make way for housing and for Rongotai aerodrome. A comparatively sandy area also exists at the head of Tapiri Bay, and a few sand dunes still remain along the Seatoun foreshore. The coastal platform supports a rather stunted grass cover with scattered prostrate shrubs, and a similar association is found on the lower hill slopes. On the latter, however, growth is generally more vigorous and in places where there is a certain amount of seepage, almost luxuriant. The major part of the area would be fully exposed to southerly gales. The population pattern of Acaenas in this area (Fig. 5) is not nearly so straightforward as at Prince of Wales Park. The most common type, indicated by the letter H. on the map, could not be assigned to any known species. The type marked P? was at first identified as Acaena novae-zelandiae var. pallida but later comparisons showed it to be smaller than the common type of that species in all respects. The type marked P. was indentified as Acaena novae-zelandiae var. pallida. Specimens in various herbaria indicate that this variety was also quite common on the formerly existing sand dunes at Lyall Bay. Only one plant of Acaena novae-zelandiae (marked N) and four plants of A. anserinifolia (marked A) were found and these were at some distance from the unidentified populations. Ring counts were not attempted in this area, but many plants had quite thick woody parts at the base which resembled those collected at Prince of Wales Park. Seeds were collected from three Hand one P? colony, from one plant of Acaena novae-zelandiae var. pallida, from one plant of A. novae-zelandiae and from two plants of A. anserinifolia. The plants of Acaena anserinifolia and A. novae-zelandiae differed in minor details only from the forms at Prince of Wales Park.