Rhodanthe Manglesii. - A most delightful plant, from the new English colony at Swan River; it is one of the tribe called everlasting, from its remaining perfect throughout the winter, if gathered when in bloom, and resembles the Helichrysum. A plant exhibited at a meeting of the London Horticultural Society, measured from eighteen inches to two feet in height, and was covered with hundreds of open flowers, and expanded rosy buds; it remained in blossom three months.