Crataegus rivuloadamensis

J. B. Phipps & O’Kennon

J. Bot. Res. Inst. Texas 1: 1065, plate 7.3a, fig. 13. 2007.

Common names: Adams Creek hawthorn
Endemic
Treatment appears in FNA Volume 9. Treatment on page 634. Mentioned on page 506, 633.

Shrubs or trees, 25–40 (–50) dm, wide-branching. Stems: twigs: new growth dark reddish green, pubescent, 1-year old shiny, dark redbrown, 2-years old dark reddish and gray; thorns on twigs ± straight, 1-year old glossy, very dark redbrown, older dark gray, shorter conic, stout, 1.5–2.5 (–3) cm. Leaves: petiole length 25–35% blade, eglandular or sparsely sessile-glandular, stipitate-glandular at leaf base, adaxial sulcus densely pubescent; blade ± elliptic or broadly elliptic to rhombic-elliptic, 2–4 cm at anthesis, 4–8 cm mature, base cuneate to narrowly cuneate, lobes 2–4 per side, max LII (0–) 5–20 (–25) %, lobe apex subacute to broadly cuspidate, margins finely crenate-serrate or serrate, veins 4–6 per side, hardly impressed, apex acute, abaxial surface glabrous or sparsely hairy young, veins appressed-scabrous, adaxial ± densely appressed-scabrous (indumentum persisting). Inflorescences 4–10-flowered; branches ± densely tomentose; bracteoles ± reddish, narrow, margins densely sessile-glandular. Flowers 17–21 mm diam.; hypanthium densely pubescent except sometimes distally; sepal color not recorded, broadly triangular, 3 mm, margins greenish, abaxial surface glabrous, adaxial pubescent; petals pale cream; anthers pink; styles 3–5. Pomes 1–5 (–6) per infructescence, pale reddish purple, becoming deep red to reddish plum and burgundy, suborbicular to broadly turbinate, 10–12 mm, usually ± densely hairy; sepals ± patent to recurved, 4–5 mm; pyrenes 3–5, dorsally strongly grooved, sides plane to very shallowly concave.


Phenology: Flowering late May–early Jun; fruiting Aug–Sep.
Habitat: Thickets, under light shade of aspen
Elevation: 800–1200 m

Discussion

Crataegus rivuloadamensis is known only from the western half of the Cypress Hills and is most abundant at elevations above 1150 m. The extremely dark young wood and short and conic thorns show strong resemblance to species of the Eurasian sect. Sanguineae Zabel ex C. K. Schneider. The unpitted pyrenes are a marked difference. The petals appear to be pale cream rather than pure white.

Selected References

None.

Lower Taxa

None.
... more about "Crataegus rivuloadamensis"
glabrous +  and hairy +
0.8 cm8 mm <br />0.008 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
James B. Phipps +
J. B. Phipps & O’Kennon +
compound +  and simple +
opposite +  and alternate +
cuneate +  and narrowly cuneate +
rhombic-elliptic +  and elliptic +
8 cm80 mm <br />0.08 m <br /> (12 cm120 mm <br />0.12 m <br />) +
broadly elliptic +  and elliptic-oblong or elliptic-rhombic +
4 cm40 mm <br />0.04 m <br /> (8 cm80 mm <br />0.08 m <br />) +
adnate +  and distinct +
crowded +, scattered +  and alternate +
Adams Creek hawthorn +
Alta. +  and Sask. +
not +  and aggregated +
800–1200 m +
1.7 cm17 mm <br />0.017 m <br /> (2.1 cm21 mm <br />0.021 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 />) +
stipitate-glandular +
dark reddish and gray +, dark redbrown +, green +  and dark reddish +
old +  and new +
Thickets, under light shade of aspen +
constricted +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
crassinucellate +
deciduous +
craspedodromous +
serrate +  and crenate-serrate +
glandular-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 +
sessile-glandular +  and eglandular +
eglandular +
stipitate-glandular +
Flowering late May–early Jun +  and fruiting Aug–Sep. +
adnate +, free +, connate +  and distinct +
dark gray-brown +  and russet +
exfoliating +  and corrugated +
red +  and reddish plum and burgundy +
0.8 cm8 mm <br />0.008 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
suborbicular +  and broadly turbinate +
1 cm10 mm <br />0.01 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
J. Bot. Res. Inst. Texas +
not arillate +
persistent +
free +  and distinct +
less patent +  and recurved +
triangular +  and broadly triangular +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
1-50-flowered +  and few-leaved +
concave +  and plane to very +
free +  and distinct +
branched +  and simple +
persistent +
distinct +
exsert +  and lateral +
elongate +
glabrous +  and tomentose +
Crataegus rivuloadamensis +
Crataegus (sect. Unassigned) ser. Montaninsulae +
species +
2.5 cm25 mm <br />0.025 m <br /> (3 cm30 mm <br />0.03 m <br />) +
dark gray +  and dark redbrown +
straight +
older +  and old +
slender +  and stout +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
craspedodromous +  and gland-tipped +
inconspicuous +
straight +
scabrous +  and glabrous +
appressed-scabrous +
4 +  and 6 +
tree +  and shrub +