414 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 30 



Franseria species growing where the Ammobroma was found but we 

 did find a considerable number of Dalea {Parosela) emovyi^ none, 

 however, showing it as host to Ammobroma. 



In number of plants harboring the root parasite, Coldenia ycHmeri 

 easily led with about 80 per cent of those found. Coldenia plicata 

 came next with about 19 per cent, and Eriogonum deserticolum sup- 

 ported the parasite in only three instances of the many examined 

 by us. Coldenia palmeri was more numerous than Coldenia plicata 

 but not in as great a percentage as the relative infestation would 

 indicate. 



The two species of Coldenia mentioned herein are quite common 

 in the arid and sandy portions of the Southwestern United States. 

 Under favorable growing conditions, Coldenia palmeri Torr. often 

 appears semispherical, sometimes spreading as much as 21/^ feet 

 and reaching a height of 1 foot. In dry seasons it presents a very 

 ragged aj^pearance and makes little, if any, growth, depending upon 

 the amount of moisture available. Its roots are very dark in color 

 and extend comparatively long distances into the sandy soil. When 

 the sand of the dunes of Imperial County contained moisture, we 

 noticed frequent enlargements of the Coldenia roots, indicating a 

 tendency to store moisture when available. It shows much better 

 growth where richer soil is available than that to be found in the 

 sand dunes, but apparently Ammobroma prefers almost pure sand. 



Eriogonum deserticolum Wats, was quite numerous but seemingly 

 not a suitable host. One contact found on Eriogonum was notable 

 in that 25 Ammobroma stalks were growing from a single contact 

 on one root of the host, the largest number found from one plant. 

 However, the stalks were small and wilted and the heads were also 

 small and not well developed. The depth was less than the average, 

 being only a little over 2 feet, while the average for Ammobroma 

 on Coldenia was between 2i/2 to 4 feet, one extreme depth being 5 

 feet. This particular case was impressed upon us by the labor 

 entailed in digging it out in the hot desert sunshine with the tempera- 

 ture at about 105°. A careful search failed to reveal any other 

 plants utilized as host, although representatives of other genera 

 were fairly abundant in the immediate locality, among which may 

 be mentioned: Covillea glutinosa Kydb., Ephedra tvifurca Torr., 

 Abronia villosa Wats., Var. au7'ita Jepson, Mentzellia tnulti-fiora 

 Gray, Stillingia annua Muell., Palafoxia linearis Lag., Parosela 

 emo7'yi Gray, Petalonyx tliur-hevi Gra}^, Oenothera trichocalyx 

 Nutt., Oenothera scapoidea T. &. G., and Dicoria canescens T. & G. 



The Papago and other Indians of the southwestern United States 

 regard this plant very highly as food. Where Ammobroma was 

 found, we noted many pieces of broken Indian pottery, some of it 

 worn very thin by blown sand. Ammobroma was discovered by Col. 



