What an odd name. It sure sounds interesting, like some sort of exotic fruit tree. Alas; argyle apple is a eucalyptus; to be specific, Eucalyptus cinerea. Compared to most other eucalypti, it stays rather low. It barely gets as tall as a two story house, even if it gets broad enough to shade most of the backyard. The rusty brown bark becomes roughly furrowed. The irregular branch structure can be quite sculptural.
The main attraction of argyle apple is the aromatic silvery foliage. Young trees are outfitted with circular juvenile leaves that are attached directly to the stems without petioles (leaf stalks). Lanceolate adult leaves are as silvery as juvenile foliage is. (Juvenile foliage of most other eucalypti is more colorful than adult foliage is.) Aggressive pruning of small trees keeps foliage juvenile for a long time.
Actually, those who know how to work with it might pollard or coppice argyle apple. Pollarding eliminates all foliated stems at the end of winter, but for the rest of the year, allows vigorous arching canes of very silvery juvenile foliage to spread outward from a few stout limbs on top of a trunk. Coppicing allows the same sort of growth from stumps just above grade.
Although a relatively small agave, the Queen Victoria agave, Agave victoriae-reginae, is also one of the most striking. Mature plants form dense foliar rosettes that are between only a foot, and a foot and a half tall and wide. What is so striking about them is the abundance of stout succulent leaves that can be so densely set that some older plants look like big, round and green pine cones.
Genetic variability within the species is considerable though; so not all plants will be so well rounded. Some resemble dark green aloes while young. All are adorned with distinctive white stripes on leaf margins, and wherever the leaves were touching the margins of other leaves before they unfurled. At least one cultivar is also variegated with white, and another is variegated with yellow.
Queen Victoria agave is bold either in the ground or in a large pot. Wherever it goes, it wants full sun exposure, and should be out of the way. The terminal foliar spines are very sharp! It does not need much water, but prefers occasional watering. Old rosettes might bloom with tiny pale white flowers on dramatic three or four foot tall spikes, but then die as they get replaced by basal pups.
Yuccas are almost as useful as aloes are for gardening in chaparral or desert climates. I say ‘almost’ because most are not quite as friendly. The leaves are outfitted with nastily sharp tips. It is how they protect themselves from grazing animals in the wild, but it is not such an advantage in home gardens. Some actually have the potential to be dangerous where someone could bump into them. The leaves of Joshua tree can puncture leather. Some types of yucca get so big that they make it difficult to avoid their nasty leaves, even if planted in the background.
That being said, for those of us who do not need to worry about endangering children, dogs or anyone else out in our gardens, yuccas are very distinctive and handsome plants. Their striking foliage radiates outward from dense foliar rosettes. Large spikes of creamy white flowers that bloom in summer or autumn stand above the foliage quite boldly. Some yuccas produce remarkably tall floral spikes. Our Lord’s Candle, Yucca whipplei (Hesperoyucca whipplei), is a terrestrial yucca that sits low to the ground, but produces a huge flower stalk that stands ten feet tall! Modern garden varieties of Adam’s needle, Yucca filamentosa, are variegated.
Of the yuccas that develop sculptural trunks, only a few are available in nurseries. The giant yucca, Yucca elephantipes, is almost too common in mild climates, and unfortunately develops a massively distended trunk that is too big for some of the situations it gets into. Most other trunk forming yuccas that grow slower are uncommon because they are susceptible to rot in landscapes where they get watered through summer.
Except for a few tropical yuccas that are very rare, yuccas are very drought tolerant. Even in desert climates, some yuccas survive on annual rainfall. Others are happier if watered a few times through summer. Giant yucca happens to be a tropical yucca, but surprisingly does not need much water.
Giant yucca is very easy to propagate from cuttings of the big canes. Even big pieces can be cut and stuck as cuttings. However, most of the tree yuccas are difficult to propagate.
Terrestrial yuccas that do not develop trunks are generally easy to propagate by division of pups, although some are difficult to handle. Some terrestrial yuccas actually develop small trunks that creep along the ground, or maybe stand a few feet tall. They can be propagated as cuttings like giant yucca.
Dracaena palm, Cordyline australis, is not a palm at all. It is more closely related to yuccas. (Incidentally, a few yuccas are also inaccurately known as palms as well, but that is another story.) The simple specie that grows taller than a two story house is rare nowadays. It develops a high branched canopy of evergreen olive drab foliage. The three inch wide leaves are about three feet long.
Modern cultivars stay significantly shorter, with somewhat shorter and less pendulous leaves. Some are nicely bronzed or purplish. Others are variegated with creamy white, pale yellow or pinkish brown. Trusses of minute flowers that bloom in early summer are not much to look at, and drop sawdust-like frass as they deteriorate. Bloom might be greenish white or blushed, and then fades to tan. Most modern cultivars do not bloom much, or may not bloom at all. The gray trunks have an appealingly corky texture.