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Yucca desmetiana

By Adam Black
Another highlight in our nursery inventory and our plant of the month, is a regularly asked- about specimen on our Peckerwood Garden tours. This distinctive and mysterious yucca is unlike any other, with a lot of conflicting information surrounding its true identity.
Originally described in 1870 from a cultivated plant, more recently folks have suggested it could be a hybrid of natural or garden origin, but it may be a naturally occurring species – I don’t know if anyone really knows for sure.
They can be seen growing staked for vertical growth near the Pool Plaza.
Yucca desmetiana may want to creep along the ground when the stems get too long_ or they can be staked up.
Yucca desmetiana  may want to creep along the ground when the stems get too long, or they can be staked up.
Adding to the confusion are a variety of names it has been offered under in cultivation, including Yucca x desmetiana (reflecting the hybrid theory), Yucca aloifolia ‘Purpurea,’ Y ucca samuelii, and cultivar names including ‘Blue Boy’ and ‘Spellbound,’ all appearing to be the same plant. Though there are reports of it flowering in cultivation, I can’t find any photos, and to my knowledge it has never flowered here. Its chalky blue-green foliage displays purple blush on the new foliage, which intensifies after some winter chilling. Unlike many other species, this yucca has soft rubbery leaves that won’t result in loss of blood. A smaller-statured species, it starts with an erect stem that will produce a cluster of additional stems from the base, but with poor structural integrity it will eventually start leaning under its own weight and soon be scrambling in a twisting manner along the ground, which can create an interesting effect spilling over rocks, especially when it produces multiple stems. John made an interesting grouping of them near the pool plaza where they are staked up, but when they get too tall and lanky for his liking they get cut back to allow new stems to take their place. It is also great for containers, and maybe even a large hanging basket when it starts creeping around.
Its main requirements is sun to partial shade in well-draining soil. It easily tolerates our region’s extremes of heat and cold without any issues. Come purchase one from our nursery while they last.
The chill-intensified purple blush that fades somewhat when the temperatures warm.
The chill-intensified purple blush that fades somewhat when the temperatures warm.
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Quercus glauca

This beautiful evergreen Asian oak tends to form multiple trunks bearing a dense crown of glossy green leaves with chalky blue undersides.

Peckerwood is known for its extensive oak collection, especially those from John’s Mexican collections, but we do have a variety of Asian oaks as well. A few decades ago, John imported seeds of Quercus glauca, also known as the Japanese Blue Oak or Ring-Cupped Oak. They germinated well and were offered through Yucca-do Nursery locally and via mail order, but according to John none sold, presumably due to being just too unfamiliar to collectors at that time. After sitting around for a while, they were eventually planted around the Peckerwood and Yucca-do properties. As they attained significant size, people finally began to notice what attractive evergreen trees they had become, with spreading branching structure, multiple trunks and smooth polychrome bark in shades of silver, white, light green and grey. Many did not immediately recognized these trees as oaks, being the thick, stiff glossy leaves with dark green tops and chalky blue undersides didn’t look remotely like any familiar North American oak. The spreading branching structure was especially appealing, combined with the naturally dense crown. These trees began producing seed –recognizable as a standard oak acorn, but with concentric rings encircling the cap, hence one of the common names (Ring-Cupped Oak). With mature trees to behold in the garden, and now offspring, there were now customers lined up for the opportunity to finally grow this tree that had to earn its admiration over time in the Peckerwood landscape.

Quercus Glauca

Quercus Glauca

20160421_151443I have been fortunate to see Q. glauca in Taiwan where it is native. It occurs in low elevation tropical forests that are rather dry, yet when grown in colder areas it is quite tolerant of hard freezes it would not otherwise see naturally. It does get some damage in zone 7 but excels in zone 8 to 10. It seems adaptable to any location with well-drained soil and full sun to light shade. I think the best specimens are attained in full exposure, starting out as a compact tree with a fairly upright habit, and eventually producing additional trunks that spread gracefully outward. If grown in shadier conditions, it will grow more vertical, less spreading, as it reaches for the light. Examples of both forms growing in these different conditions can be observed at Peckerwood, and both have their merits.

In March, the new growth emerges a purple-bronze color that is quite attractive, and when the tree is a little older this growth will be accompanied by hanging catkins of flowers.  Of particular note are the trees on the west side of the nursery property, as they did not receive any supplemental water in the most recent prolonged drought, yet they really never missed a beat. Taiwan was in a severe drought when I visited in early 2015, and many adjacent natives were clearly wilted and suffering while Q. glauca looked flawless.

— Adam Black

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Dyschoriste linearis – Snake Herb

Dyschoriste linearis

Dyschoriste-thin-leaf-form-available-in-nursery

Dyschoriste linearis

Some might expect a “plant of the month” to be some exceptionally rare and boldly attractive plant. This month I wanted to focus on a groundcover that at first glance may seem quite humble in many ways, but is in fact incredibly versatile and has a unique charm of its own. I always liked Dyschoriste after growing a Florida native species prior to my move, but assumed others would never see its attractive qualities over the more flashy options. Shortly after starting at Peckerwood, I was surprised to find that one of our most reliable volunteers, Craig Jackson, shared my appreciation of the patch of Dyschoriste linearis that John has growing along the perennial border near the south entrance to the woodland garden. I then began to see that nurseries here in Texas actually carry this plant, and soon found that, when offered in our nursery, others were attracted to it and bought it, shattering my assumptions!

Snake Herb is an evergreen Texas native that is drought tolerant, cold hardy and low maintenance, with dense, weed-suppressing foliage that looks attractive year around. Dyschoriste linearis is a highly variable plant, with leaves that can be either thin and needle-like, or slightly more

20160602_190805

Dyschoriste linearis

broad and elliptical. John’s plant is the broad-leaf form, but the linear-leaved form seems to be more common in the nursery trade. Both are equally attractive and create a low, dense mat of 8” to 12” tall evergreen stems that gradually form a tight, tidy clump. Throughout the warmer months, purple flowers resembling smaller versions of the related Ruellia are readily visible.

Naturally growing in dry, sunny spots in sandy or gravelly open areas, this plant is amazingly tolerant of neglect following establishment, after which water should only be necessary following long dry spells. The dense mat it forms tends to be compact and tight, but occasionally an errant runner will result in a random patch or two forming a short distance away from the main plant. Some may prefer to remove any satellite clumps if you are keeping a more formal, organized landscape, but for naturalizing it is simply a matter of preference. It is in no way an aggressive spreader, so it will not become something you regret planting and removal of undesired shoots easy.

South entrance to the Woodland Garden

In addition to its xeric qualities, snake herb will also grow in fertile garden soil with regular irrigation,

Quercus-oblongifolia

Quercus oblongifolia

provided there is excellent drainage and at least a fair portion of the day in full sun. Design ideas utilizing this plant include planting around bold foliage, like around the base of thick, succulent Agave leaves, or as a foreground layer in front of or in-between taller specimen perennials or low shrubs. I think its color and texture goes well with silver colored foliage. Gravel mulch around the plant really helps make the clump stand out compared with wood mulch or bare earth.

Don’t be put off by the common name “Snake Herb”, it does not attract snakes any better than other ground covers. In fact, I can’t readily find out why it has that common name. Other species elsewhere in the world, some of which form taller shrubs, have many cultural medicinal uses, and perhaps somewhere it has been used to treat snakebite. Quite possibly it is instead named for its long snakelike rhizomes which results in its ability to form a colony. Either way it is a valuable addition to any well-drained sunny landscape.

We currently have the needle-leaf form available in our nursery, but we are also rooting divisions of John’s elliptical-leaved form. Adam will be bringing a Florida collection of Dyschoriste oblongifolia to trial in Texas, and there are several other species native to the southern US to seek out in an attempt to broaden the palette of snake herb varieties that can be utilized for all their desirable qualities.

— Adam Black

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Nannorrhops ritchiana – The Mazari Palm

A true oddity, Nannorrhops adds color, texture and interest to any garden.

With a native range extending from Yemen to Pakistan, Nannorrhops ritchiana inhabits among the most hostile environments of any palm. Summer brings temperatures above 100F while winters can dip well below freezing. Rainfall is seasonal leaving the palm well adapted to extended drought.

Despite these harsh origins, the Mazari palm is a hardy, adaptable species growing successfully in South Texas, California and Florida. Its deeply split palmate leaves range in color from gray-green to pale blue with a virtually unarmed petiole making it safe for planting along paths and walkways. It will sucker from the base and each stem is covered with a thick rust colored tomentum.
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Rare for palms, Nannorrhops exhibits above ground (dichotomous) branching, growing multiple heads from the main stem. Once a stem flowers, it will die back to the main stem, which continues to grow and branch further.

In Peckerwood Garden you can see the Nannorrhops in the South Dry Garden above the “Tall Drifter” sculpture by Peter Reginato.

Zone: 8 and higher
Soil: Adaptable to most soils given good drainage and is salt and limestone tolerant
Exposure: Part to full sun
Tolerates extreme drought but grows faster with regular irrigation and fertilizer
10ft or higher but trunks often recline with age

— Adam Black

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Cephalotaxus harringtoniana ‘Korean Gold’

On the subject of winter interest, one unusual conifer demands attention this time of year. During warmer months, the upright Japanese plum yew selection Cephalotaxus harringtoniana ‘Korean Gold’ leaves observers wondering why a dark green plant has such a name. Only after a few late fall cold snaps will the show really start, when the outer foliage is gilded with bright yellow highlights and contrasts sharply with the dark green inner needles. This winter coloration is produced through an interesting process called “photoinhibition”. During winter when the plants are dormant and physiological functions are slowed down, they undergo a temporary change that allows them to deal with excessive sunlight that would normally be utilized for photosynthesis during the warmer months of the year. This change of color is not to be confused with fall color on deciduous trees, as these colored needles will not fall off.  On the subject of winter interest, one unusual conifer demands attention this time of year. During warmer months, the upright Japanese plum yew selection Cephalotaxus harringtoniana ‘Korean Gold’ leaves observers wondering why a dark green plant has such a name. Korean-GoldOnly after a few late fall cold snaps will the show really start, when the outer foliage is gilded with bright yellow highlights and contrasts sharply with the dark green inner needles. This winter coloration is produced through an interesting process called “photoinhibition”. During winter when the plants are dormant and physiological functions are slowed down, they undergo a temporary change that allows them to deal with excessive sunlight that would normally be utilized for photosynthesis during the warmer months of the year. This change of color is not to be confused with fall color on deciduous trees, as these colored needles will not fall off.

Many conifers will show photoinhibition to a slight degree if conditions are consistently cold, appearing in winter as light green to slightly golden, or in some specie bronze, brown or reddish purple. Even loblolly pines will have a slight, barely noticeable light green to gold hue after some cold weather. However, certain rare individuals will display photoinhibition to an excessive degree, visually appearing a bright shocking gold, and these notable examples become popular winter garden subjects. Korean-Gold-(2)There are several cultivars of pines, hemlocks, firs and spruces that are as yellow as a school bus in winter, then revert back to normal green in summer.

Unfortunately there are few of these selections that are adaptable to southeast Texas, or they will thrive but simply don’t receive enough chilling to attain the coloration in USDA zones 8-9. Cephalotaxus harringtoniana ‘Korean Gold’ is one of the few that will develop color in winter in this area, most prominently in the inland sections away from the warming influence of the gulf. Though plum yews are most often utilized in shady garden settings, most will also happily take nearly full sun but might require a little more irrigation. In order for ‘Korean Gold’ to attain the best winter color it will require this sort of open exposed conditions. In sheltered areas it will remain plain green, no different than the regular form of upright (fastigiate) C. harringtoniana.

 

-Adam Black

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Senecio aschenbornianus

Senecio aschenborneanus

Senecio aschenbornianus was a new one for me upon starting here last month. I had grown many other members of this genus from North American natives, South African succulent species, as well as Asian representatives too. I was quite drawn to the color and shape of the blue/gray foliage which somewhat resembled a shrunken oak leaf hydrangea. The multi-stemmed shrub held this beautiful evergreen foliage in a naturally dense manner. Though it looks very tender, the plant is remarkably hardy in our area, without any blemished leaves through the several freezes we’ve had. Normally walking around with my head to the ground looking at every plant I am passing, I was stopped in my tracks yesterday by a sudden sweet fragrance that I couldn’t immediately place. Prying my eyes up to survey the surroundings for the source resulted in an instant visual impact of school-bus yellow mounds of Johns grouping of three plants. The buds that had been on the plant since January had all suddenly opened seemingly overnight. During one of my always-enlightening walks in the garden with John, I had remarked on my great appreciation for this plant based on foliage alone, figuring the flowers would be simply an added bonus. He mentioned not collecting it for years as it was “everywhere” in Mexico, and being so abundant it was just seemingly less of a priority while out searching for the few-and-far-between treasures. Fortunately he did finally collect it and now I can’t wait to propagate it for others to enjoy as much as I have. John has grown it in the dappled sunlight of a high overhead tree canopy and has endured zone 8b winters like a champ. It is being grown in a well-drained setting with supplemental irrigation only when necessary and seems pretty ironclad once established. Check in later this year for this plant’s availability in our nursery.

— Adam Black

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Cycads: Pictures of Antiquity by Carl Schoenfeld

Cycads are woody plants that superficially resemble palms and tree ferns. They are found around the world in both hemispheres in tropical and subtropical zones. There are 11 genera of Cycads, some of which are Zamia and Dioon. In the mainland United States we have one species of Cycad – Zamia floridana.

Male Dioon
Male Dioon plant

It is a native of Florida and extends into southern Georgia and is referred to as Cootie. It is used widely in Florida as a drought tolerant landscape accent. Here at Peckerwood the Florida Coontie was the first Cycad tried; it has proliferated, setting enormous fruit bearing cones with bounties of fertile seed. That led the way for others.

In 1988 John Fairey and I collected seed of Chamal (Dioon edule var. angustifolia) in northeastern Mexico. These germinated and after twelve years are about 16 inches tall and have about eight leaves atop a small swollen stem (caudex). Cycads are extremely slow growing to our eyes but we must understand that they have been around for over 200 million years. Notice their distinctive character which reflects their antiquity.

Photos show them in habitat with close-ups of the flowering or reproductive structures in both sexes. A detail of the fertile cone with maturing seed reiterates their simplicity. The last image is a detail of the rigid leaf, which is retained for some number of years.

Female Dioon plant
Female Dioon

Dioons are ancient woody plants and some very large specimens could possibly be several hundred years old. They inhabit steep hillsides where the soils are skeletal and poor. In areas were the decomposed shale is deep they proliferate and create an unreal prehistoric setting, dominating the environment. Chamal can also be found in more hospitable soils and shelter, but there they are small and scattered. Interestingly, Dioon edule specifically has the ability to contract its stem underground as it grows — thus maintaining relativity in the amount of trunk exposed. One suggested explanation for this strange (unplant-like) activity is to reduce its exposure to environmental stress and predation — remember these plants were around during the time of dinosaurs. Also, they may go through prolonged periods of rest, revealed as narrowing in the diameter of the trunk. Some feel that these plants are not regenerating at this time. Are they possibly endangered or just taking a rest that will wait out our short impatient lifetimes? The greatest danger to their existence is ignorance and apathy. They truly are unequalled and intriguing living organisms that count the eons of time while we count the seconds.

— Carl Schoenfeld