11 



C. Biogeographic and phylogenetic history: 



Lesguerella humilis is possibly most closely 

 related to a group of species that includes L. 

 hemiphysaria . its nearest relative (Rollins 1984), 

 L. cordifolia . L. kinqii , L. palmeri , and L. 

 peninsularis (Rollins and Shaw 1973) . All of 

 these other species occur in the Great Basin and 

 adjacent Baja California. None are sympatric with 

 L. humilis . 



Lesguerella humilis occurs in high altitude sites 

 (upper subalpine and alpine) , a habitat that was 

 probably more widespread during the late 

 Pleistocene and during colder climatic periods 

 more recently. However, the small geographic range 

 of L. humilis may be related also to edaphic 

 conditions as well as climate. 



6. General environment and habitat description 



A. Concise statement of general environment and 

 habitat: Lesguerella humilis occurs in sparsely 

 vegetated areas in the upper subalpine krummholz 

 zone, and in alpine fellfield areas above the 

 upper treeline. On St. Mary Peak, the krummholz 

 consists of wind-trimmed individuals of Pinus 

 albicaulis (white-bark pine) . The associated 

 herbaceous vegetation is characterized by a 

 mixture of species, including: Astragalus 

 kentrophyta var. implexus (Thistle milkvetch) , 

 Dicentra uniflora (Steer 's-head) , Draba spp. 

 (Draba) , Dryas octopetala (White dryas) , Erigeron 

 simplex (One-flower f leabane) , Eritrichium nanum 

 (Pale alpine forget-me-not) , Haplopappus lyallii 

 (Lyall's goldenweed) , Hulsea alqida (Alpine 

 hulsea) , Ivesia qordonii (Gordon's Ivesia) , 

 Pedicularis contorta (Coiled-beak lousewort) , 

 Sedum lanceolatum (Lance-leaved stonecrop) , 

 Smelowskia calycina (Alpine smelowskia) , and 

 Veronica cusickii (Cusick's speedwell). 



The populations occur on coarse-textured soils 

 (sandy or gravelly) derived from metamorphic 

 rocks. The sites are on moderately steep slopes 

 and ledges, and on level exposed areas at 

 elevations of 2685 to 2925 m (8800 to 9590 ft.). 



B. Physical characteristics 

 1. Climate 



