Hybridization between diploid cultivars of poinsettia results in abundant seed production. However, with the diploid used as the ~naternal parent in crosses with tetraploids, less than 1% viable seedlings are realized. Cytological observations indicated a 2:3:2 chron~osome number rario of the embryo, endosperm and maternal tissue in diploid crosses with endosperm development completed in about 45 days after pollination. Embryo differentiation in diploid crosses occurred at 26 days and 111atured in approximately J-t days after pollination. T h e chromosome number ratio of the embryo, endosperm, and maternal tissue was not firmly established for the diploid x tetraploid cross due t o the small number of viable seeds obtained, but the expected 3:4:2 ratio was frequently observed. Endosperm developnlent in most of the ovules examined did not progress beyond the large fragile cell stage. This study suggests that the endospernl may be the determining factor in setting of seed in the diploid X tetraploid cross.'Present address:
Pyrus calleryana, Decne, `Aristocrat'; Cryptomeria japonica, D. Don; Populus maximowiczii, Henry × `Androscoggin' and Koelreuteria bipinnata, Franch. trees were grown in low-profile containers. The optimum height and width of these containers was 20 to 30 cm and 84 cm, respectively. Pine bark and mixtures containing 50% or more of pine bark were preferable to mixtures containing leaf mold for filling the containers because the former weigh less. Roots penetrated pine bark mixtures better than sphagnum peat mixtures and also retained their shape better during transplanting. When grown in low-profile containers, trees grew fibrous root systems; after transplanting, roots grew downwardly radial and trees were able to withstand extremely difficult landscape conditions.
6-Furfurylaminopurine (kinetin) applied directly to the poinsettia (Euphorbia pulcherrima willd.) bud at 1 ppm was effective in inducing axillary shoot stimulation.
Gardenia jasminoides Ellis, an evergreen shrub native to China but grown in the southern United States, is one of about 60 subtropical species of the genus Gardenia. Gardenia jasminoides is a variable species that grows from 0.6 to 1.8 m tall with 10-cm-long leaves and 8-cm-diameter flowers. Synonymous names are cape jasmine, G. florida L., G. radicans Thunb., and G. augusta Merr. According to Bailey (1949), the gardenia, commonly known as G. veitchi, is a presumed selection of the cultivar Fortuniana Lindl. (G. fortunei Hort), which also belongs to this species. Gardenia is interesting to southern landscapers because it is a compact evergreen shrub with fragrant, white flowers and glossy, dark-green leaves. Gardenia is attractive to the nursery industry because it is easy to propagate from cuttings and grow in containers. However, G. jasminoides lacks hardiness. It is reliably grown in portions of the U.S. Dept. of Agriculture's plant hardiness zone 7b but not in 7a. Being a variable species, some cultivars are hardier than others, but the hardiest local survivor has been single flower.
Ilex cornuta ‘Burfordii’ holly plants were maintained at 3-4°C for 0, 2, 4, 6 or 8 weeks. Following these treatments, the number of flowers to develop were greatest on plants receiving 6 or 8 weeks of chilling. Time required for flowering to begin and the duration of flowering was shortened by the longer exposures to cold treatment
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