#The following is a detailed description of a two year-old plant of the new cultivar as grown in a two-gallon container under natural light (full sun), outdoors in Waterloo, Wis. Phenotypic differences may be observed with variations in environmental, climatic, and cultural conditions. The color determination is in accordance with the 2001 R.H.S. Colour Chart of The Royal Horticultural Society, London, England, except where general color terms of ordinary dictionary significance are used. Botanical classification: ‘McKCitrine’ is a cultivar of Forsythia viridissima. Parentage: Naturally occurring branch sport of Forsythia viridissima ‘Bronxensis’. General description: Plant habit.—Compact, mounded, deciduous shrub. Height and spread.—61 cm in height and 76 cm in spread. Hardiness.—USDA Zone 4. Culture.—Tolerant to most soils in full sun to part shade. Full sun is required for best foliage color. Diseases and pests.—No susceptibility or resistance to other diseases or pests known to effect Forsythia viridissima has been observed. Root description.—Fibrous. Growth and propagation: Propagation.—Softwood stem cuttings. Root initiation.—7 to 14 days when grown at 20 to 25° C. in a greenhouse without supplemental lighting under mist or high humidity. 1200 PPM IBA applied to base of cuttings enhances rooting. Time required for root development.—4 to 6 weeks of root development is required before shifting into a 2 gallon container. A 2-gallon container is marketable in 2 years. Stem description: Shape shape.—Round, solid. Stem color.—New wood; 144A turning to an intermediate color between 144A and 146B then 146A. Old wood; 146A with an overlay of 148D as the stem becomes woody. Stem diameter.—Typically about 1.5 to 2 mm in new growth, up to 7 mm in diameter at base. Stem surface.—Glabrous on younger stems, becomes glaucous in appearance with small nodules on woody stems. Internode length.—Typically 1.5 to 2 cm (0.5 to 2 cm between leaves). Branching.—About 7 to 9 basal branches on 2 year old plants, typically 7 to 10 secondary branches (often in opposite pairs) on a 30 cm branch without pinching. Suckers from the crown grow upright and should be headed back. Pinching increases branching and reduces internode lengths. Branches typically range 10 to 22 cm in length. Foliage description: Leaf shape.—Oblanceolate. Leaf division.—Simple. Leaf base.—Attenuates to petiole. Leaf apex.—Acute. Leaf venation.—Upper surface; conspicuous, typically 3 to 4 pairs of lateral veins from midrib, color consistent with margin color. Lower surface; Not conspicuous, vein color consistent with color of leaf centers. Leaf margins.—Serrated, average of 8 serrations per side on a leaf 5 cm in length. Leaf attachment.—Petiolate. Leaf arrangement.—Opposite. Leaf surface.—Glabrous on upper and lower surfaces. Leaf length.—4 to 5 cm (mature leaves, not including petiole). Leaf width.—1 to 1.5 cm (mature leaves). Leaf emergence.—Leaf out is typically observed about the first week in May in Wisconsin. Leaf color.—Immature: New leaves in spring often emerge solid 2C (yellow) and develop into margins and centers as they mature. After margins develop (about a week) and newly emerged leaves in mid summer have the following color pattern. Upper; margins are N144A to N144B (yellow-green) with centers 144A (darker yellow-green), Lower; margins N144A with centers N144A, margins are not as conspicuous. Mature: Upper; margins range from 145A to 144A to 144B to 155B with centers ranging from 137B to 138B. Lower; margins range from 147B to 147C with centers 147B, margins are not as conspicuous as upper surface. Margins on mature leaves are typically 2 to 5 mm in width. Petiole size.—1 to 1.5 cm in length, about 1 mm in width. Petiole shape.—Sulcate. Petiole color.—144A. Stipules.—Very small, at base of petioles, remains as buds (not leafy). Flower and seed production: Flowering has not been observed under the conditions tested.