Crataegus ×bicknellii

Crataegus ×bicknellii (Eggleston) Eggleston

Bull. Torrey Bot. Club 38: 244. 1911.

Endemic
Basionym: Crataegus rotundifolia var. bicknellii Eggleston Rhodora 10: 79. 1908
Synonyms: C. chrysocarpa var. bicknellii (Eggleston) E. J. Palmer
Treatment appears in FNA Volume 9. Treatment on page 636. Mentioned on page 522.

Shrubs or trees, 30–80 dm. Stems: twigs: new growth greenish, glabrous, 1-year old tan, older darker or grayer; thorns on twigs few to numerous, 1-year old dark-brown, ± stout, 2–6 cm. Leaves deciduous; petiole slender, length 50–70% blade, adaxial sulcus sparsely hairy, eglandular to barely glandular; blade broadly elliptic, 4–6 cm, base cuneate, lobes 4 or 5 per side, short, LII 10–15%, lobe apex acute, margins basally entire, otherwise serrate, veins 5 or 6 per side, adaxially impressed, apex acuminate, abaxial surface glabrous, adaxial sparsely scabrous young, glabrescent. Inflorescences 7–15-flowered; branches glabrous; bracteoles conspicuous, 7–10 mm, membranous, linear, margins glandular-serrate, proximal ones sometimes very long. Flowers 16–23 mm diam.; hypanthium glabrous; sepals 7 mm, margins glandular-laciniate; stamens 10, anthers dull purple; styles 3–5. Pomes red, ± orbicular, 10–12 mm diam., glabrous; sepals persistent, reflexed; pyrenes 4 or 5, dorsally grooved, sides plane or roughened with obscure cavities.


Phenology: Flowering Jun; fruiting Sep–Oct.
Habitat: Brush
Elevation: 0–10 m

Discussion

Crataegus ×bicknellii is known only from Nantucket Island; it is a good example of a small population of a rare hawthorn known to have persisted about 100 years. Palmer assigned C. ×bicknellii to C. chrysocarpa; it is not much like var. chrysocarpa in leaf shape, indumentum, or glandularity, nor in its striking laciniate sepals, nor purple anthers. Crataegus ×bicknellii also flowers much later than the C. chrysocarpa group. The author agrees with E. P. Kruschke (1965) that it is closest to C. sylvestris. The specimens seen by the author have glabrous pedicels in contrast to the slightly villous pedicels reported by Eggleston and Palmer. The flowers in recently collected material are fewer per inflorescence and much larger than described in the protologue.

Selected References

None.

Lower Taxa

None.
... more about "Crataegus ×bicknellii"
0.8 cm8 mm <br />0.008 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
James B. Phipps +
Crataegus ×bicknellii (Eggleston) Eggleston +
compound +  and simple +
opposite +  and alternate +
cuneate +
Crataegus rotundifolia var. bicknellii +
8 cm80 mm <br />0.08 m <br /> (12 cm120 mm <br />0.12 m <br />) +
less ovate +  and narrowly elliptic or obovate +
4 cm40 mm <br />0.04 m <br /> (6 cm60 mm <br />0.06 m <br />) +
0.7 cm7 mm <br />0.007 m <br /> (1 cm10 mm <br />0.01 m <br />) +
adnate +  and distinct +
crowded +, scattered +  and alternate +
not +  and aggregated +
0–10 m +
1.6 cm16 mm <br />0.016 m <br /> (2.3 cm23 mm <br />0.023 m <br />) +
unisexual +  and bisexual +
not +  and aggregated +
not +  and aggregated +
yellow +  and red or purplish +
0.6 cm6 mm <br />0.006 m <br /> (2 cm20 mm <br />0.02 m <br />) +
grayer +, darker +, tan +  and greenish +
older +, old +  and new +
Brush +
constricted +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
crassinucellate +
deciduous +
glandular-serrate +, serrate +  and entire +
glandular-laciniate +
inferior +  and superior +
biseriate +  and clustered +
collateral +  and basal +
0.8 cm8 mm <br />0.008 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
elliptic +  and circular +
0 (?) +  and 4 (?) +
free +  and distinct +
Flowering Jun +  and fruiting Sep–Oct. +
adnate +, free +, connate +  and distinct +
dark gray-brown +  and russet +
exfoliating +  and corrugated +
1 cm10 mm <br />0.01 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
orbicular +
Bull. Torrey Bot. Club +
not arillate +
persistent +
free +  and distinct +
triangular +
7 cm70 mm <br />0.07 m <br /> (?) +
1-50-flowered +  and few-leaved +
free +  and distinct +
branched +  and simple +
persistent +
distinct +
exsert +  and lateral +
elongate +
glabrous +  and tomentose +
C. chrysocarpa var. bicknellii +
Crataegus ×bicknellii +
Crataegus +
species +
6 cm60 mm <br />0.06 m <br /> (10 cm100 mm <br />0.1 m <br />) +
2 cm20 mm <br />0.02 m <br /> (6 cm60 mm <br />0.06 m <br />) +
craspedodromous +  and gland-tipped +
inconspicuous +
few +  and numerous +
6 +  and 5 +
tree +  and shrub +