Although they arose too late to qualify technically as Old Garden Roses, the hybrid musks are often informally classed with them, since their growth habits and care are much more like the Old Garden Roses than Modern Roses. The hybrid musk group was mainly developed by Rev. Joseph Pemberton, a British rosarian, in the first decades of the 20th century, based upon 'Aglaia', an 1896 cross by Peter Lambert. A seedling of this rose, 'Trier', is considered to the foundation of the class.[4] The genetics of the class are somewhat obscure, as some of the parents are unknown. Rose multiflora, however, is known to be one parent, and Rosa moschata (the musk rose) also figures in its heritage, though it is considered to be less important than the name would suggest. Hybrid musks are disease-resistant, repeat flowering and generally cluster-flowered, with a strong, characteristic "musk" scent.[17] The stems tend to be lax and arching, with limited thorns.[7] Examples include 'Buff Beauty' and 'Penelope'.