The parents of this unintentional hybrid are supposedly American sycamore and Oriental sycamore. No one really knows. London plane, Platanus X acerifolia, appeared within a private collection in London at the middle of the Seventeenth Century. It became popular there two centuries later, through the Victorian Era, because of its resilience to pollution.
Mature London plane trees might be taller than a hundred feet. Few here are old enough to be much taller than sixty feet though. Regardless, defoliation of such grand deciduous trees might be overwhelming through autumn. Foliar tomentum (fuzz) can be surprisingly irritating while raking too much foliage. Autumn color is unimpressively brownish yellow. The specific epithet ‘acerifolia’ translates to ‘maple foliage’, because the foliage resembles that of Norway maple.
London plane remains among the most common of street trees. It really is commendably adaptable to inhospitable urban situations. However, it is not perfect. Its roots eventually displace pavement. The foliar canopies can eventually grow disproportionately broad for compact urban parkstrips. For some people, the foliar tomentum can be a major allergen.
Of all the nut trees that are actually quite easy to grow, the chestnut, Castanea (various specie and hybrids), has somehow become the most obscure. It probably lost popularity while native forests in eastern North America were being annihilated by rampant disease (which never became such a threat in the west), but may be unpopular simply because it can get so big. Mature trees are regularly more than seventy feet tall and nearly as broad.
Chestnut trees are productive for those who like the nuts, but simply very messy for those who do not. The smooth meaty nuts are contained within offensively spiny husks known as ‘burrs’. A few varieties of chestnuts fall freely from the burrs. Most need to be separated from their burrs even after they fall to the ground. The evenly serrate leaves will soon be turning amber gold or brown for autumn.
This might be the most spectacular and most reliable of autumn foliage available locally. Sweetgum, Liquidambar styraciflua, begins to develop a brilliant blend of yellow, orange and red in response to the earliest mild chill of autumn. It defoliates slowly to retain much of its colorful foliage through the earliest rain and wind of winter, and perhaps even later.
Sweetgum leaves are palmate, and about four inches wide, with five pointed lobes. One very rare cultivar has hierarchically lobed leaves, with lobes on lobes. Another has blunt lobes. Some cultivars as well as individual trees favor particular foliar colors for autumn. ‘Burgundy’ exhibits more dark red color than typical, and retains foliage later than typical.
Mature trees can grow fifty feet tall, but are not very broad. They can get taller and lankier to compete with other tall trees. Their upright form conforms to grove arrangement within large landscapes and parks. Unfortunately, their aggressive roots can displace concrete. Their branches can be structurally deficient. Their spiky and hard fruit can be obnoxious.
Yellow centered blue flowers like those of the familiar potato bush, on vines almost like those of the comparably familiar potato vine would be like the not so common Chilean nightshade, Solanum crispum. However, Chilean nightshade needs to be trained onto support in order to climb, and only reaches fifteen feet or so. The cultivar (cultivated variety) ‘Album’ is like a shrubbier redundancy to potato vine, since it has white flowers. ‘Glasnevin’ is the most popular cultivar because it flowers freely and is hardier to frost.
The nearly inch wide and slightly fragrant flowers bloom in small clusters from May or June until about now. Small but sometimes prominent green berries that turn yellowish orange and then dark purple are toxic. Partial shade inhibits bloom and vigor.
Bearded iris are famously diversely colorful. Not much lacks from their floral color range. Spuria iris, Iris spuria, are quite different. Their floral color ranges only from purplish blue to bright white, all with prominent yellow throats. The least rare of this rare species is the subspecies carthaliniae, almost all of which blooms white. Seed is generally true to type.
Seed might be abundant without timely deadheading. However, propagation is easier by division of the copiously branching rhizomes. Such rhizomes are fibrous and tough, with comparably tough and wiry roots. They migrate to develop broad colonies, which should appreciate thinning every few years. They rarely get too crowded to bloom nicely though.
Spuria iris blooms for almost two weeks during late spring or early summer. Two or three flowers bloom in succession on stems that are nearly as high as their deciduous foliage. Leaves are elegantly narrow and upright like those of cattail, but get only about three feet tall. Carthaliniae subspecies defoliate later than others, which defoliate through summer, then foliate for autumn.
The diminutive and indistinguishably dense flowers of Anthurium are surprisingly pathetic relative to the flashiness of the ‘spathe and spadix’ structures that accompany them. The spadix is the generally conical structure that supports and is covered with the flowers. It is most often pale shades of white, yellow or green, but can be pink or purplish. The spathe is the solitary, colorful bract that surrounds the spadix. It is most often white, red or burgundy, but can be orange, pink or pale shades of yellow or green.
There are nearly a thousand known specie of Anthurium. Most but certainly not all have glossy foliage. Leaf shape and size is as variable as flower color. Most Anthurium are terrestrial understory plants that grow below higher canopies of tropical mountain forests of Central and South America. Others are epiphytes that cling to trees, or lithophytes that cling to rock outcroppings.
Around the home, they are mostly grown as houseplants as much for their rich green foliage as for their colorful blooms. In the garden they need shelter from direct sunlight and frost. Blooms, and perhaps other parts, are toxic.
Hollywood juniper had formerly been the only popular juniper of tree form. As it became less popular during the past few decades, cultivars of the once obscure Rocky Mountain juniper, Juniperus scopulorum, became more popular. Also, a few more modern cultivars became available. Now, the once overly common Hollywood juniper is quite uncommon.
Rocky Mountain juniper is naturally rather grayish for protection from the harsh exposure of the high elevations which it inhabits. Cultivars are grayer, bluish or silvery, and mostly develop symmetrically conical form. Old specimens that were initially conical eventually grow as small trees with rounded and relatively dense canopies, perhaps on bare trunks.
‘Skyrocket’ and ‘Blue Arrow’ are very narrow like Italian cypress that grow only fifteen feet tall. ‘Wichita Blue’ and ‘Moonglow’ are stoutly conical. ‘Blue Arrow’ and ‘Wichita Blue’ are bluish green. ‘Skyrocket’ and ‘Moonglow’ are silvery gray. Established specimens do not require much water, but develop better foliar color with warmth and occasional watering.
The excellent and remarkably brilliant shades of yellow, orange, red and burgundy of the foliage in autumn suggest that sweetgum, Liquidambar styraciflua, is from New England. However, it is native between New Jersey, Florida and the eastern edge of Texas, as well as isolated forests of Central America. It actually prefers mild climates to where winters are too cold. Mature trees are generally columnar (relatively narrow) and less than fifty feet tall where well exposed, but can get more than twice as tall to compete in forests.
Unfortunately, mature sweetgum trees can be somewhat problematic in urban gardens. Limbs are often weak enough to break in wind, or if they get too heavy from the weight of their own foliage. Also, the abundant round seed pods are outfitted with nasty spikes, like little maces almost two inches wide. They are painful to step on, and can actually be quite hazardous.
By the end of the Victorian Period, dracaena palm, Cordyline australis, had become very popular, both as small trees and as foliar plants. The largest specimens were only about twenty feet tall and half as wide. Removal of trunks that grew too tall for short foliar plants induced fresh basal growth. The drab leaves grew three feet long and three inches wide.
Cultivars with bronzed foliage became more popular after the Victorian Period, although not as common as the original. They grew slower and stayed smaller. The many modern cultivars of the past few decades stay even smaller, with even more impressively colorful foliage. Most are purply bronze or variegated with creamy white, pale yellow, pink or tan.
Modern cultivars generally mature efficiently, but then attain height too slowly to function as small trees. Some do not develop substantial trunks. They are therefore more popular for their delightful foliar color and texture. Many generate appealingly pendulous foliage. However, a few eventually develop sculptural form with exposed corky trunks and limbs. Removal of unimpressive floral panicles prior to bloom removes floral frass before it gets messy.
Autumn needs to get a bit cooler before bower vine, Pandorea jasminoides, will be ready to stop blooming. It may not always bloom profusely, but it does bloom for a long time, beginning with warming spring weather. Flowers can be white, pink or white with pink throats, but are most often pink with burgundy throats. Even through late autumn and winter, the glossy evergreen foliage is appealing without bloom. Mature vines can climb more than fifteen feet high. Those with variegated foliage might stay somewhat smaller.