Robinia pseudo-acacia L. - Black Locust
Family - Fabaceae
Stems - Woody, single. A
tree to +15m tall. Bark tan to light grayish. Paired spines present on
younger branches. New seasons growth angled, sparsely pubescent.
Twig in winter.
Bud and spines.
Leaves - Alternate, odd-pinnate,
typically with 7-19 leaflets. Leaflets oval to elliptic, opposite, glabrous
when mature, entire, to +2cm long, +1.5cm broad.
Inflorescence - Drooping
Axillary racemes to +15cm long. Typically 20-30 flowers per raceme. Peduncle
and pedicles pubescent.
Flowers - Corolla papilionaceous,
2cm long and tall. Standard to 1.8cm broad and long, with yellowish spot
in center. Stamens diadelphous, tube to 1.4cm long. Anthers orange, -1mm
long. Ovary green, flattened, 1.5cm long, 1.1mm broad. Style 6.5mm long,
pubescent at apex, upcurving near apex. Calyx tubular, bilabiate, sparsely
to moderately pubescent, green mottled with red. Upper lip 3-4mm long,
notched at apex. Lower lip 3-lobed. Lobes 2.5mm long. Fruits compressed, +1cm wide, +/- 7cm long.
Calyx.
Fruit, slightly larger than life size.
Flowering - May - June.
Habitat - Slopes, pastures, open woods, streambanks, roadsides.
Origin - Native to U.S.
Other info. - This tree is
very common and is easily noticed when flowering. The flowers have a pleasant
fragrance but each cluster only last a few days. My dad, who is the master
of all things green and growing, recognized it from his days in Europe,
where the tree also grows.
Photograph taken in Columbia, MO., 2-21-04 and 5-11-04.
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