Alice Le Duc
Alice (Jack) Le Duc
Several collecting trips in Mexico, in association with a monographic revision of a portion of the genus Mirabilis, have produced several species which show promise as new perennial landscape plants. Mirabilis pringlei Weatherby, with its showy pink flowers, has potential as a striking summer blooming plant, particularly when used as a container accent plant. Equally promising are two as yet unnamed species, their fragrant white flowers opening in the evening, seem ideal as terrace or patio accents.
Alice Le Duc
Greg Osterhaus and Alice Le Duc
An anatomical study was conducted to determine and compare the internal leaf surface to volume (S/V) ratio of the spongy mesophyll in selected cultivars of Acer saccharum. A low S/V ratio is one of several selectively advantageous characteristics associated with xerophytic plants. It has been proposed that a correlation exists between certain injuries produced by environmental stress and plant leaf anatomy. The taxa included in the study were Acer saccharum cvs. Green Mountain and Legacy, A. saccaharum Caddo and Wichita Mountain (seedlings of Caddo County and Wichita Mountains, Oklahoma relictual populations respectively), and A. saccharum ssp. nigrum (syn. Acer nigrum). Leaf samples were taken from five different representative trees for each of the five cultivars. The results showed that Caddo, which is highly stress tolerant, had a significantly lower internal S/V ratio than the other four cultivars. `Legacy' which is intermediate in stress tolerance had the next lowest S/V ratio. As expected the highly injury-susceptible selections A. saccharum `Green Mountain' and A. saccharum nigrum had high S/V ratios. However, the Wichita Mountain variety which exhibits a stress tolerance similar to Caddo, also had a high S/V ratio. These results suggest that other factors may be involved in determining environmental stress tolerance.
Alice Le Duc and Mary Lewnes Albrecht
J.R. Schroeder and Alice Le Duc
Ten culinary and ornamental herbs were evaluated for time and quality of rooting of tip cuttings. The taxa included in the study were oregano (Origanum vulgare), lemon thyme (Thymus ×citriodorata), applemint (Mentha suavolens), Persian catnip (Nepeta ×faassenii), lemon balm (Melissa officinalis), southernwood (Artemisia abrotanum), caraway thyme (Thymus herba-barona), hyssop (Hyssopus officinalis), `Blue Wonder' catnip (Nepeta `Blue Wonder'), pineapplemint (Mentha suavolens var. variegata). Four replicates of each species were used. The cuttings, untreated and rooting hormone treated, were placed under intermittent mist, then cuttings potted when a 1- to 1.5-inch root ball had developed. Most of the stock suffered from some chlorosis during rooting; southernwood cuttings particularly displayed severe chlorosis which was overcome with 2 weeks of constant-feed fertilizer after potting. Oregano displayed the best results, rooting in seven days with or without treatment. It produced a sellable 4-inch pot in 31 days from sticking the cuttings. Lemon thyme, applemint, Persian catnip, and lemon balm all rooted in 14 days if treated. No difference was observed in days to rooting between treated and untreated lemon thyme. Untreated cuttings of lemon balm, applemint, and Persian catnip rooted in 25 to 30 days. Treated applemint cuttings not only rooted more quickly but produced a marketable 4-inch pot in significantly less time. Southernwood and caraway thyme rooted in 25 days, with no significant difference between treated and untreated cuttings. Hyssop, pineapplemint, and `Blue Wonder' catnip took about 30 days, also with no significant difference between treated and untreated cuttings.
Alice Le Duc and John C. Pair
Five cultivars of boxwood (Buxus microphylla)—'Winter Gem', B. microphylla var. japonica `Green Beauty', `Green Velvet', `Green Mountain' and `Glencoe'—were planted in twelve different exposures at Manhattan and Wichita, Kan., representing USDA hardiness zones 5 and 6 respectively. The 1995–96 winter was one of great extremes. Lows of –25°C for Manhattan and -23°C for Wichita were recorded, along with sharp 24-hour temperature drops of 31–32°C in January and March. Differences in cultivar performance were noted between the sites. At the Wichita site best winter color was exhibited by `Green Velvet' and `Glencoe', whereas `Green Mountain' sustained some bronzing of foliage due to winter sun. At Manhattan only `Glencoe' in protected locations exhibited good winter color. All other surviving cultivars showed considerable bronzing. In addition, `Green Beauty' was severely damaged at Manhattan, sustaining bark splitting due to low temperatures, although most plants survived at Wichita. Shaded locations on north, northeast and northwest produced best plant quality of all cultivars; whereas, the poorest plant performance occurred on south and southeast exposures.