Crataegus williamsii

Eggleston

Bull. Torrey Bot. Club 36: 641. 1909.

Common names: Williams hawthorn
Endemic
Treatment appears in FNA Volume 9. Treatment on page 504. Mentioned on page 502, 503, 505.

Shrubs, 40–60 (–100) dm. Stems: expanding bud-scales conspicuous, coral red; twigs: new growth glabrous, 1-year old deep reddish-brown; thorns on twigs ± straight to slightly recurved, black, sometimes dark purple young, older paler, shiny, ± slender, 3–4 cm. Leaves: petiole 2–3 cm, ± hairy, eglandular or glandular; blade rhombic to elliptic, 4–6 cm, thin, base cuneate, lobes 2 or 3 per side, short, lobe apex acute, margins ± evenly sharp-serrate except at base, teeth ± inconspicuously gland-tipped, veins 4 or 5 (or 6) per side, apex acute, abaxial surface glabrous, veins hairy, adaxial shortly and densely appressed-hairy. Inflorescences 8–20-flowered; branches sparsely villous; bracteole margins sessile-glandular. Flowers 16 mm diam.; hypanthium glabrous or densely villous externally; sepals ± narrowly triangular, 4–7 mm, margins finely glandular-serrate, abaxially glabrous; stamens 10, anthers pink; styles 3 or 4 (or 5). Pomes usually pale-red young, bright red (late Aug), deepening to oxblood red or darker mature (Sep), usually short-ellipsoid, 8 mm diam., longer than wide, sparsely villous; sepals not thickened or enlarged, spreading to reflexed, narrow, 4–7 mm; pyrenes 3 or 4 (or 5), sides variably pitted.


Phenology: Flowering May–Jun; fruiting Sep–Oct.
Habitat: Scrub
Elevation: 700–1000 m

Discussion

Crataegus williamsii occurs in the Clark Fork and Flathead drainage basins of northwestern Montana; possible records for Idaho require more study. The species is notable for its extremely late anthesis, after sympatric C. macracantha; it is the last hawthorn to flower in its area of occurrence. The immature fruit is bright red, in contrast to its later duller color. The fall color of the foliage is predominantly crimson burgundy or a pallid version thereof. Crataegus williamsii is the most distinct member of ser. Purpureofructus because of its relatively small and delicate, spreading to reflexed fruiting sepals (versus accrescent, long, erect-patent) and its lack of purple to black colored, fully mature fruit. See also comments under 26. C. macracantha.

Selected References

None.

Lower Taxa

None.
... more about "Crataegus williamsii"
0.8 cm8 mm <br />0.008 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
James B. Phipps +
Eggleston +
exfoliating +  and plated +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
compound +  and simple +
opposite +  and alternate +
cuneate +
8 cm80 mm <br />0.08 m <br /> (12 cm120 mm <br />0.12 m <br />) +
rhombic +  and elliptic +
4 cm40 mm <br />0.04 m <br /> (6 cm60 mm <br />0.06 m <br />) +
dark gray-brown +
expanding +
adnate +  and distinct +
crowded +, scattered +  and alternate +
Williams hawthorn +
not +  and aggregated +
700–1000 m +
16 cm160 mm <br />0.16 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 />) +
reddish-brown +
old +  and new +
Scrub +
villous +  and glabrous +
constricted +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
crassinucellate +
deciduous +
obscure +  and evident +
glandular-serrate +  and sharp-serrate +
denticulate +
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 +
post-mature +
glandular +  and eglandular +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
Flowering May–Jun +  and fruiting Sep–Oct. +
adnate +, free +, connate +  and distinct +
coriaceous-leaved +
dark gray-brown +  and russet +
exfoliating +  and corrugated +
darker +, red +, deepening +, bright red +  and pale-red +
8 cm80 mm <br />0.08 m <br /> (?) +
longer than wide +
mature +  and young +
short-ellipsoid +
Bull. Torrey Bot. Club +
not arillate +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
persistent +
free +  and distinct +
spreading +  and reflexed +
triangular +
enlarged +  and not thickened +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
1-50-flowered +  and few-leaved +
shallow +  and deep +
free +  and distinct +
branched +  and simple +
persistent +
distinct +
exsert +  and lateral +
elongate +
glabrous +  and tomentose +
Crataegus williamsii +
Crataegus (sect. Douglasia) ser. Purpureofructus +
species +
5 cm50 mm <br />0.05 m <br /> (7 cm70 mm <br />0.07 m <br />) +
paler +, dark purple +  and black +
straight +
older +  and young +
slender +
3 cm30 mm <br />0.03 m <br /> (4 cm40 mm <br />0.04 m <br />) +
gland-tipped +
inconspicuous +
1 +  and few +
straight +
determinate +
5 +  and 4 +