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elm-leaf blackberry

Canadian or smooth highbush blackberry, ronce du Canada, smooth blackberry

Habit Shrubs, 30–50 dm, unarmed or armed. Shrubs, 5–30 dm, unarmed or armed.
Stems

biennial, erect, then arching, usually moderately, rarely sparsely, hairy hairs stellate, eglandular, strongly pruinose;

prickles absent or sparse to dense, erect to hooked, stout, 3–10 mm, broad-based.

biennial, arching, glabrous, eglandular or sparsely sessile- to short-stipitate-glandular, not pruinose;

prickles absent or sparse, erect or slightly retrorse, slender, 2–5 mm, narrow- to broad-based.

Leaves

persistent or nearly so, ternate to palmately compound;

stipules filiform to linear, 4–12 mm;

leaflets 3–5, terminal ovate, elliptic, or suborbiculate to obovate, 4–10 × 2–6(–9) cm, base rounded to cuneate, unlobed, margins finely to moderately serrate, apex acute or acuminate to attenuate, abaxial surfaces with hooked prickles on larger veins, densely white short-velutinous, hairs usually minute, eglandular.

deciduous, usually palmately compound, lustrous;

stipules filiform to narrowly lanceolate, (5–)8–15(–22) mm;

leaflets (3–)5, terminal ovate to elliptic, (3–)7–9(–11) × (3–)4–5(–6) cm, base rounded to shallowly cordate, unlobed, margins finely to coarsely serrate or doubly serrate, apex acuminate to attenuate, abaxial surfaces sometimes with hooked prickles on midvein, glabrous or puberulent, eglandular.

Inflorescences

terminal, 10–60-flowered, paniculiform or thyrsiform.

terminal on short shoots, sometimes appearing axillary, (5–)15–25-flowered, racemiform.

Pedicels

unarmed or prickles moderate to dense, erect to hooked, densely short-hairy, eglandular.

usually unarmed, hairy, eglandular or sparsely sessile- to short-stipitate-glandular.

Flowers

bisexual;

petals usually pink, sometimes white, obovate or elliptic to suborbiculate, 5–12 mm;

filaments filiform;

ovaries apically hairy.

bisexual;

petals white, obovate to elliptic, 8–22 mm;

filaments filiform;

ovaries glabrous.

Fruits

black, globose to ovoid, 1–1.5 cm;

drupelets 10–40, strongly coherent, separating with torus attached.

black, globose to short-cylindric, 1–2 cm;

drupelets 10–75, strongly coherent, separating with torus attached.

2n

= 14.

= 14, 21.

Rubus ulmifolius

Rubus canadensis

Phenology Flowering May–Jul. Flowering May–Jul.
Habitat Woodland edges, open areas, disturbed areas, moist soil Mountainous highlands, cool, shaded intermediate regions within deciduous and boreal forests, margins of lakes and woods
Elevation 0–500 m (0–1600 ft) 0–2000 m (0–6600 ft)
Distribution
from FNA
CA; NJ; NV; OR; WA; s Europe; c Europe; n Africa [Introduced in North America; introduced also in s South America]
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; CT; DC; GA; KY; MA; MD; ME; MI; MN; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WI; WV; NB; NF; NS; ON; PE; QC; SPM [Introduced in Europe (Poland)]
[WildflowerSearch map]
[BONAP county map]
Discussion

Rubus ulmifolius can be distinguished, especially from the closely related R. bifrons and R. vestitus, by its strongly pruinose stems, finely serrate leaflets, and lack of glands throughout. Unlike R. ulmifolius, strongly pruinose native Rubus species lack relatively large and showy pink petals. Some new stems developing from tip-rooting, and early leaves on such stems (especially in shade), are not whitened abaxially and are tomentose. Such unusual stems develop typical leaves and surfaces in parts formed later.

There has been nomenclatural confusion over unarmed plants of Rubus ulmifolius (see E. Monasterio-Huelin and H. E. Weber 1996). Rubus inermis Willdenow is an illegitimate later homonym of R. inermis Pourret, and the type specimens for both names are of poor-quality. If an unarmed variety of R. ulmifolius is to be recognized, such as occurs in California, the name var. anoplothyrsus Sudre should be used instead of var. inermis (Willdenow) Focke.

Rubus ulmifolius is attractive and is potentially weedy but relatively uncommon, found primarily in coastal California from the San Francisco Bay region southward. It probably no longer persists in New Jersey, last collected there in 1897, and it is rare in Nevada and Oregon. Rubus ulmifolius likely hybridizes with R. bifrons where they co-occur; it is one of relatively few diploid and sexually reproducing species of European blackberries.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Rubus canadensis has a wide range and is the most northerly of all the highbush blackberries. The species is morphologically similar to R. allegheniensis except that the plants have little armature, are not as hairy, and have no glands. It also has characteristically lustrous leaves. The open and edge habitats in which it grows can greatly influence the phenotype, as with most highbush blackberries. At higher elevations or in poorer soil conditions, the plants are smaller; when partially shaded, leaves of primocanes may be larger. Leaves of floricanes vary in size and shape and are unreliable for identification. Because of the variation, multiple names have been erected, especially locally; it is felt that a stricter approach to defining it is prudent. Some of the names traditionally associated with sect. Canadenses (L. H. Bailey) L. H. Bailey are here associated with other Rubus species or are considered to refer to putative hybrids.

The following nothospecies names are based on putative hybrids involving Rubus canadensis and: R. allegheniensis (R. ×forestalis L. H. Bailey, R. ×immanis Ashe); R. flagellaris (R. ×lepagei L. H. Bailey, R. ×rixosus L. H. Bailey); R. hispidus (R. ×novanglicus L. H. Bailey); R. pensilvanicus (R. ×amabilis Blanchard [not Focke], R. ×amicalis Blanchard, R. ×elegantulus Blanchard [= R. canadensis var. elegantulus (Blanchard) Farwell], R. ×multilicius L. H. Bailey, R. ×noveboracus L. H. Bailey, R. ×pergratus Blanchard [= R. canadensis var. pergratus (Blanchard) L. H. Bailey], R. ×crux Ashe); R. setosus (R. ×miscix L. H. Bailey [based on R. ×peculiaris Blanchard (not R. peculiaris Sampaio)]).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 9, p. 54. FNA vol. 9, p. 37.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Rubeae > Rubus Rosaceae > subfam. Rosoideae > tribe Rubeae > Rubus
Sibling taxa
R. allegheniensis, R. arcticus, R. bartonianus, R. bifrons, R. caesius, R. canadensis, R. chamaemorus, R. cuneifolius, R. deliciosus, R. flagellaris, R. glaucifolius, R. hispidus, R. idaeus, R. illecebrosus, R. laciniatus, R. lasiococcus, R. leucodermis, R. neomexicanus, R. nivalis, R. niveus, R. nutkanus, R. occidentalis, R. odoratus, R. parviflorus, R. parvifolius, R. pascuus, R. pedatus, R. pensilvanicus, R. phoenicolasius, R. pubescens, R. repens, R. saxatilis, R. setosus, R. spectabilis, R. trivialis, R. ursinus, R. vestitus
R. allegheniensis, R. arcticus, R. bartonianus, R. bifrons, R. caesius, R. chamaemorus, R. cuneifolius, R. deliciosus, R. flagellaris, R. glaucifolius, R. hispidus, R. idaeus, R. illecebrosus, R. laciniatus, R. lasiococcus, R. leucodermis, R. neomexicanus, R. nivalis, R. niveus, R. nutkanus, R. occidentalis, R. odoratus, R. parviflorus, R. parvifolius, R. pascuus, R. pedatus, R. pensilvanicus, R. phoenicolasius, R. pubescens, R. repens, R. saxatilis, R. setosus, R. spectabilis, R. trivialis, R. ulmifolius, R. ursinus, R. vestitus
Synonyms R. discolor, R. ulmifolius var. anoplothyrsus R. argutus var. randii, R. besseyi, R. canadensis var. imus, R. illustris, R. kennedyanus, R. laetabilis, R. montensis
Name authority Schott: Isis (Oken) 1818: 821. (1818) Linnaeus: Sp. Pl. 1: 494. (1753)
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