The flowers are radially symmetrical and bisexual3 and can be solitary or distributed in racemes4, panicles or cymes or in tight clusters. The calyx5 consists of 4-6 separate sepals, and there are also 4-6 separate petals. The sepals and petals are often similar and usually overlapping like tiles on a roof in two or more series. There can be 4-18 stamens (frequently equal to the number of petals or twice the number of petals) and when in the larger numbers, are frequently in two series. The anthers frequently discharge their pollen through a flap-like arrangement. The ovary is superior6, and consists of two or more fused carpels7, but without careful examination, appear unicarpellate.
The fruit is usually a berry8 or can be dry and distribute its seeds by opening irregularly or obliquely.[ 2, 5, 10]
Holly leaved barberry, Oregon grape, mountain grape, blue barberry, mahonia à feuilles de houx
Scientific name: Mahonia aquifolium9
Synonyms: Berberis piperiana, Berberis aquifolium
Origin: North America
Plant description: Mahonia aquifolium is a spreading to erect plant that grows from 0.1 to 2m (~3.9 to 79 in) in height. The bud scales are generally deciduous (fall off, not persistent). The compound leaves have 5-9 pairs of leaflets that are rounded to elliptical, about 3 inches (~ 7.6 cm) long with about 6 to 24 spiny teeth per side around their edge. They are lustrous green on their upper surface, the lower surface is without papillae10and they can be either flat or somewhat wavy. The leaf stalks (stems) are 1-2 inches (~2.54 – 5.1 cm) long.
The flowers are in tightly bundled racemes11 to 3 inches (~7.6 cm) in length.
The ripe fruits are dark blue to blackish and while still fresh, have a blue bloom on their surface. They are egg shaped and can be attached at either their narrow or thicker end.[5, 12 & 13]
Distribution: see map.
Blooming period: Generally early spring. Williams[13] indicates in California Berberis aquifolium, depending on the variety, blooms March to June, March to May, or April to June. In the Chicago area it blooms late April, early May.[6]
Importance as honey plants: Oertel[7], from his extensive use of nationwide surveys over a several year period, found the species Berberis aquifolium to be of some importance in Oregon. Ayers and Harman[1], from their questionnaires, found the genus Mahonia to be of some importance in WA.
Pellett[8] indicates that Berberis nervosa, for its production of harvested honey, is of only minor importance near the western coast, but because it blooms early and …
