The only difference between this and R. Coulteri is a fuzzy calyx and the leaves are a little narrower. A perennial Matilija Poppy to eight feet tall. This form of Matilija Poppy has six inch flowers that are white with a yellow center. Some articles declare the flowers smaller, this doesnt appear to be factual. The flowers are wonderful mixed with sages and monkey flowers in a bouquet. At planting, all will survive in will lose sand near the coast, but 2 of 3 in the interior heat and heavy soil will die. We've planted these on many sites. The best were loose sand. The worst were clay. If you can get them to grow in clay they do not have the vigor they do in sand, but the flowers are the same size, just less of them. Water once per week for the first summer, then leave them alone. If the top gets old and woody, prune them down around Christmas. Native to a few spots in the coastal inland ranges of southern California in areas where the Tecate Cypress occurs in San Diego County and above Ojai in Ventura County. Romneya Coulteri var. trichocalyx does not seem to be as aggressive as regular Matilija Poppy. Regular Matilija grows through everything on the hillside, these plants are spaced and clumped as individual shrubs. Associated plants in the wild range from Carex spissa, Quercus agrifolia, Cupressus Forbesii, Lonicera dentata, Sambucus mexicana, Ceanothus tomentosa olivaceous, Rhus ovata, Quercus dumosa(berberdifolia), Keckiella cordifolia, Diplacus, Antirrhinum nuttallianum, Rhus laurina, etc.