| General Description | This species is considered a broad spreading deciduous tree reaching a
mature height of 4.5 m - 7 m, or a large shrub that extends 4.5 m - 6 m at full vertical growth. A cross of M. virginiana x M. tripetala as the parentage. The species was recorded as the first Magnolia hybrid in western horticulture. The current expression of this tree 'Cairn Croft’ is the fourth reincarnation of this hybrid. Although from a cultivated plant, the wild origin of this plant is not known. Thompsoniana develops a large spreading tree that broadens and adorns into a gorgeous and attractive creamy white flowering tree that correlates traits of the
parental plants. Magnolia x thompsoniana is a hardy and rarely cultivated species of Magnolia. Strangely, a viable seed has never been established for this peculiar tree. |
| ID Characteristic | The ‘Cairn Croft’ (Recently founded 1998) exists through two propagated
cuttings that reside at the Arnold Arboretum where they originated. This rare natural cultivated hybrid is only grown or found from maintained gardens. |
| Shape | An upright tree when in primary development that gradually broadens into
a decurrent habit, spreading an unequal, opened shape. Visually cited as a round-headed, unkempt crown, broad-ranged and forming a large shrub or small tree. |
| Landscape | Today, Magnolia x thompsoniana is a naturalized tree for national, public and community parks, and well observed garden areas of authenticity. Attracted by a local natural wildlife habitat, the tree is resistant to deer. Magnolia lumber is mainly used for manufacturing furniture. |
| Propagation | Propagation of the cuttings with flowers at Dana Greenhouses. |
| Cultivation | Well drained moist and fertile soil, humus and peaty rich types of earth. Organic, acidic soil; pH should range from 5.5 - 6.5. Prosperous in full to partial sun, and the tree is tolerant to heat and humidity if planted in partial shade; it is not tolerant to salt and sand spray. Moderate tolerance in high sandy, clay, loam environments and is susceptible to heavy winds. Can sustain through winters with no structural damage. |
| Pests | Pollen sterility (CMS), Cytoplasmic male sterility. Armillaria (fungi).
Susceptible to caterpillar and beetle leaf defoliation and scales. |
| Notable Specimens | Arnold Arboretum, Harvard University, Jamaica Plain, Boston, Massachusetts, United States of America. |
| Habitat | Horticultural origin. |
| Bark/Stem Description | A smooth, undefined, greyish-silvery-greenish colour with mahogany hues
scarcely blended within the bark. Stems and scions are occupied with white and silvery lenticels. Often a multi-trunk or a single tree trunk in maturity, developing to 1.5 m in diameter. The stems have an incompletely septate pith that naturally lengthens, forming into a simple green colour. Leaf scars and terminal bud scale scars mark nodes and internodes on the newly grown scions with foliage and flowers. |
| Flower/Leaf Bud Description | Terminal flower buds develop into a large, conical vase type of form,
reflecting a green to creamy golden-light beige colour. Approximately 15 cm - 20 cm in height and 2 cm in diameter. Auxiliary leaf buds
(1 cm - 2 cm) are a cylindrical shape with a greenish, pale-brown colour, producing vegetative or reproductive shoots. |
| Leaf Description | Arrangements are alternate and comprised of a simple structure of verticil leaves supported with a solid green pedicel. The single foliage length can mature to 25 cm long; standard length is 16 cm - 21 cm. The width of a sole leaf measures 5 cm - 8.5 cm wide. Large, thick, elliptic, obovate to ovate leaves flourish a deep shiny forest green on the upper surface, and a glaucous array of silver, blue, and
green is evident on the underside of the lamina blade. A definite, smooth entire margin with an unspecified number of leaves that tend to have undulating edges, edging a pinnate venation with a cuneate form at the base and an acute apex. The foliage has a paper-leathery feel with fine pubescence underneath the blade. The foliage remains existent throughout the beginning of winter seasons. The leaves will prevail the duration of a winter climate that is not exposed to a severe, inclement cold weather conditions. |
| Flower Description | The solitary corolla is a beautiful blossom of 8 to 11 tepals that whorl in a verticil pattern, ranging up to 10 cm in length and 12 cm - 15 cm across. The diameter of the corolla is 12 cm - 15 cm. A rich luxuriant of an entire margin of petals contours an obovate oblong of brilliance. An opulent, pure white creamy elegant colour illuminates the corolla, encircling a centering pistil or carpel of creamy green colour with orange-beige creamy coloured follicles. Flowers from a conical bud then developing in bloom into a white bulb, vase shaped flower, maturing into a beautiful stellate of flowers. A pleasant sweet and spicy lemon scented aroma emits from the uprightness of flowers in blossom. Flourishing, flowering throughout summer phases from mid June through to July. Each flower has perfectly structured reproductive parts, containing both the stamen and the pistil. Filaments and anthers
are a distinct structure type and on occasions are absent from this particular flower. |
| Fruit Description | The dehiscent cone-shaped fruit of aggregates reflects a light, rustic,
orange-yellowish colour of curling follicle tips on a fluorescent green elongated receptacle. Ranges from 2 cm - 3 cm in diameter and 3 cm - 5 cm in height. The fruit is not edible, and is upheld with a dark green solid pedicel with visible white lenticels or stomata. Bears a healthy red coloured fruit seed with a seedling period, beginning to produce follicles in September - October. |
| Colour Description | Bark is glaucous, a dull greyish-silvery-greenish complexion with
scarcely blended mahogany colouration. Terminal buds are a simple yellowish green. Lateral buds are greenish - light brown. An alternate whorl of foliage is a deep, shiny forest green on the upper surface of leaves. A glaucous grey bluish-green colour is present on the undersurface of leaves. The aggregate of fruit is a greenish fluorescent lime. Pinkish, turning creamy-yellowish follicles encase seeds of the bright reddish rose. Creamy white tepals of brilliance densely encircle a yellowish creamy beige pistil or carpel. |
| Texture Description | Fine, straight grain. |