Jerry M. Parsons, Tim D. Davis, Steven W. George, and Wayne A. Mackay
Texas Agricultural Extension Service, 1143 Coliseum Rd., San Antonio, TX 78219
Revised version of a feature article that appeared in the October, 1994 volume of HortScience
“Bluebonnet” encompasses all six of the Lupinus species native to Texas and is the state flower. The most popular and widespread bluebonnet, Lupinus texensis, is a winter annual that produces violet–blue(Violet–Blue group 96A, Royal Horticultural Society Colour Chart) (Royal Horticultural Society, 1982) racemes in early to mid spring and is predominately self–pollinating. This species is widely used to provide impressive floral displays along roadsides throughout much of the state (Andrews, 1986). Although pink and white color variants exist in native populations, they are quite rare. Thus, a breeding project was initiated in 1985 to develop bluebonnets with novel flower colors for use as bedding plants. ‘Abbott Pink’ was the first seed–propagated cultivar to be released from this project (Parsons and Davis, 1993). We have since used recurrent phenotypic selection for lavender flower color to develop ‘Barbara Bush’. This cultivar is intended for use as a bedding plant and is named after the former First Lady and wife of former US President George Bush. A ceremonial naming of the cultivar occurred at Texas A&M University on 9 March 1994.
Seed was collected by the senior author in the spring of 1987 from a small patch of lavender–flowered bluebonnets that appeared in a seed production field of pink–flowered plants (the progenitors of ‘Abbott Pink’) in LaPryor which is located in south central Texas. To our knowledge, this novel flower color had never been previously observed. The seed from these plants was planted in the fall of 1987 and produced a population containing about 80% lavender–flowered plants the following spring which were allowed to randomly mate. The remaining 20% of the plants had violet–blue or pink flowers and were rogued as soon as their color was visible. Seed was collected in the spring of 1988 from the remaining lavender–flowered plants and planted out in the fall. Recurrent phenotypic selection for lavender flowers was repeated for two more years (one cycle per year) until a pure lavender–shaded population was obtained. This line has been grown in isolation for two additional years and is now being released as ‘Barbara Bush’. Seed collected from ‘Barbara Bush’ will remain pure if plantings are isolated from other bluebonnets.
Young plants form a dense rosette in the fall and then bloom the following March or April. The bloom period is 3 to 5 weeks. The plant produces 100–200 racemes/m2 ground surface. The mildly fragrant racemes are shades of lavender (Royal Horticultural Society Violet Group 84C–93B), 8–12 cm long, and each raceme contains 25–40 florets. The last racemes produced during the season tend to be shorter than the first racemes. Each floret is 1–2 cm long and has a 3–6 mm wide white banner spot in the center of the banner petal. This spot often turns to reddish purple (Royal Horticultural Society Red–Purple Group 61A–B) with age, but the florets sometimes shrivel before the color change takes place. Pedicel length is 6–12 mm and flower spike stem diameter is 2–4 mm. At full bloom, the plants are 30–50 cm tall, 50–70 cm in diameter, and have a mounded form. The foliage is yellow–green (Royal Horticultural Society Yellow–Green Group 146B) and is composed of alternate, palmately compound leaves generally with 5 leaflets (occassionally with 6). Each individual leaflet is oblanceolate, 3–5 cm long, and 12–16 mm wide at the widest position. Petiole length is 4–6 cm. Pods (30–50 mm long and 6–10 mm wide) become visible about one month after anthesis, are densely pubescent, and contain 4–7 seeds each. Weight per 100 seeds is about 3.5 g. Seeds are light brown occasionally speckled with black.
Seed must be scarified to obtain optimal germination (Davis et al., 1991). Concentrated sulfuric acid treatment of 30–60 minutes is generally satisfactory for scarification. Irrigation or rainfall is needed to induce germination, but once plants are established, they require little additional irrigation under central Texas climatic conditions. The plants overwinter in USDA Hardiness Zones 8–10 (U.S. Department of Agriculture, 1990) and often survive winter in Zone 7. ‘Barbara Bush’ grows well in most soilless media for production of bedding plants. However, the plants must be maintained under well–drained conditions to avoid problems with damping off and other as yet unidentified root rots. Chilling is not required for flowering.
Except for having a different flower color, the garden performance of ‘Barbara Bush’ is nearly identical to the native violet–blue bluebonnet and the previously released ‘Abbott Pink’ (Parsons and Davis, 1993). Plants have been grown from seed in the greenhouse and successfully transplanted outdoors at the following diverse Texas locations: San Antonio (4 years at several different sites); Dallas (2 years); LaPryor (4 years); Center (2 years); El Paso (1 year). Comparative trials at these locations revealed no differences in garden performance between ‘Barbara Bush’ and the native violet–blue bluebonnet.
Seed of ‘Barbara Bush’ can be purchased from Texas Seed Co., P.O. Drawer 599, Kenedy, TX 78119–0599.
Andrews, J. 1986. The Texas bluebonnet. Univ. Texas Press, Austin, Tex.
Davis, T.D., S.W. George, A. Upadhyaya, and J. Parsons. 1991. Improvement of seedling emergence of Lupinus texensis Hook. following seed scarification treatments. J. Environ. Hortic. 9: 17–21.
Parsons, J.M. and T.D. Davis. 1993. ‘Abbott Pink’ bluebonnet (Lupinus texensis Hook.) HortScience 28: 65–66.
Royal Horticultural Society. 1982. Royal Horticultural Society Colour Chart. London.
U.S. Dept. of Agriculture. 1990. Plant hardiness zone map. Misc. Publ. 1475, Agr. Res. Serv., Wash. D.C.