Harpephyllum_caffrum_2c

Wild Plum Trees

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Despite their common name and habit of producing edible fruit, wild plum trees (Harpephyllum caffrum) are not closely related to the plums trees that produce the fruit that fills the shelves of your local grocer (those plums belong to the genus Prunus). In fact, aside from these factors, wild plums (also called Kaffir plums) do not have much in common with their more well-known counterparts at all.

Geographic Range

Native to portions of southeastern Africa, wild plums are primarily restricted to low-lying coastal areas that have sufficient rainfall to support forests. They are particularly common in riparian habitats, which provide them with both the direct sunlight and moisture they need to thrive. They do not tolerate frost, so they are only found in areas that remain above 32 degrees year-round.

Basic Information and Description

The only members of their genus, wild plum trees can reach respectable sizes; the largest may approach or exceed 50 feet in height. Each of the tree’s pinnately compound leaves bears one terminal leaflet and eight to 16 lateral leaflets. Watery sap often leaks from places in which the leaves have been broken or cut. This helps to distinguish wild plums from Cape ash trees (Ekebergiacapensis), which they strongly resemble.

Wild plums are dioecious trees, meaning that individual trees bear only male or female versions of the small, off-white flowers. Following insect-driven pollination, the female flowers develop into green fruit, which begin appearing by early- to mid-summer. By autumn, they ripen and turn red.

Most of their leaves are glossy and light- to emerald-green, although the trees often bear a few randomly scattered red leaflets. A thin waxy coating protects the evergreen leaves from water loss, allowing them to persist throughout the year. The leaves are generally positioned at the ends of the tree’s branches, which helps give the tree a thick, attractive crown.

Wild Plums: An Important Food Source

Many people living alongside wild plum trees relish the species’ slightly sour fruit. Wild plums are slightly smaller and more oval than American plums, but otherwise look relatively similar. They are eaten raw, made into jams and fermented to make wild plum wine.

Wild plum fruit are also an important food sources for many different wildlife species that share their range. Mammals are especially important wild plum consumers. Fruit bats rely heavily on the fruit and serve as important seed dispersers for the trees, as are bush pigs and bush babies. Several birds also relish the species’ fruit, including trumpeter hornbills and purple-crested turacos.

Additionally, the larvae of at least eight different butterfly and moth species feed upon the leaves of wild plums, and birds use the hollow trunks of plum trees as roosting sites.

Cultivation and Commercial Use

Wild plums are popular ornamentals that are grown in private and public areas throughout much of South Africa. Most are grown from seeds, but others are the product of cuttings. Once established, wild plum trees are very low-maintenance ornamentals, which usually thrive if planted in U.S.D.A. Hardiness Zones 10 through 11.

Several native cultures have used the bark of the tree medicinally throughout history. The pale, red wood of wild plums is attractive, but it is very heavy and not particularly durable. Accordingly, it is primarily used in low-impact applications, such as furniture and other interior goods.

Mango

Mango Trees (Mangifera spp.)

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The common mango tree is the most widely planted and well-known member of the genus Mangifera.  Designated by botanists as Mangifera indica, the tree is most famous for its delicious fruit, which is enjoyed by people all over the world. Mango trees are also grown ornamentally in yards large enough to accommodate their impressive size.

Basic Description

Common mango trees are quite attractive. They have dense, evergreen crowns, full of lance-shaped leaves, arranged alternately along the stems. Their yellow or white flowers are small, but attractive, and born on long magenta stalks. The fruit are large and come in a multitude of colors, from nearly purple to orange to bright red. The fruit are not only relished by humans; many wildlife species, especially mammals, feed heavily on the large fruit.

Mango trees grow quickly, and like most other trees that do so, they require direct sun exposure. They have moderately high water needs, but once established they are moderately drought tolerant. The most frustrating problem associated with ornamental use is the species’ tendency to shed branches, flowers and leaves on a nearly constant basis, thereby creating rather significant litter problems. Additionally, their branches are susceptible to damage in high winds.

Superlative Size

The common mango tree is one of the tallest fruit trees in the world. While most are between 30 and 50 feet tall, exceptional specimens may exceed 100 feet in height. Mangos also boast impressive crown spreads, which usually have diameters of about 50 feet, but 125-foot-wide trees are not unheard of. Mangos have massive trunks, which may have circumferences in excess of 20 feet.

Mangos live relatively long lives by fruit tree standards, which is part of the reason they are capable of reaching such immense sizes. Several trees are known to have produced fruit for three centuries.

Origin and Current Distribution

Common mango trees were originally native to portions of Burma, India and Pakistan. They are thought to have been domesticated around 2,000 B.C. By 500 A.D., the tree had been introduced to the Philippines and scattered locations in Southeast Asia, and within the last 500 years, the tree was introduced to Africa and Brazil.

India is the world’s leading producer of mangos – they produce approximately 63 percent of the world’s total crop. Other important mango-producing countries include Mexico, Pakistan, China, Indonesia and the Philippines.

Toxic Compounds

Mangos are an edible fruit; but like most other members of the sumac family (Anacardiaceae), they possess urushiol in their outer skin. Urushiol is the same chemical found in poison ivy (Toxicodendron radicans), pacific poison oak (Toxicodendron diversilobum) and poisonwood trees (Metopium spp.), and it can cause a serious allergic reaction in sensitive individuals. Accordingly, it is important to wash mangos thoroughly before consuming them.

Urushiol is also found in the sap of the plant, so it is wise to handle freshly cut wood with gloves. Because mangos produce an abundance of urushiol-laden smoke when burned, the wood of these trees should never be used for grilling, fireplaces or outdoor fires.

The Family Tree

The genus Mangifera contains nearly 30 different described species, although some authorities only consider about 10 of these to be valid. Some of these species, such as the white mango (Mangifera caesia) are common and grown commercially, while others, such as the Kasturi (Mangifera casturi), are of no commercial importance and are extinct in the wild. Many of these mango relatives produce edible fruit, but some are dangerously poisonous before ripening.

One of the most interesting members of the genus is the Kwini (Mangifera odorata). An aptly named tree, the Kwini can often be smelled before it is seen in its forest habitat. The tree produces a distinct, pleasant fragrance all year long, but it becomes especially strong when the tree flowers.

Nolina Plants

Beargrasses (Nolina spp.)

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While most beargrasses (Nolina spp.) look rather similar, two traits characterize every species in the group: tall, pale inflorescences and serrated, grass-like leaves.

Some species produce a thick, woody trunk-like stem, but others lack such structures entirely. Most of the 25 to 28 species assigned to the genus inhabit a range that extends from the southern United States to southern Mexico.

Beargrasses should not be confused with soap grass (Xerophyllum tenax), which is also called a beargrass by some.

Basic Description

Beargrasses are best described as perennial herbs, which produce leaves in crowded rosettes. In addition to their attractive growth form, many species – especially palmilla (Nolina microcarpa) – have a pleasing fragrance.

Drought- and fire-tolerant plants, beargrasses grow best when provided with ample, direct sunlight. In fact, beargrasses appear to be well adapted to periodic wildfires, and they often colonize areas that have recently experienced fires.

Beargrasses produce tall flower stalks called panicles, in the spring or early summer. Each panicle contains hundreds or thousands of tiny flowers.  While most authorities believe that beargrasses achieve crosspollination via the wind (which partially explains their habit of producing tall flower stalks), the flowers attract a wide variety of bees, wasps and other nectar-feeding insects.

Arid Adaptations

Once established, many beargrasses are capable of living very long lives in extremely harsh conditions.

Two Florida beargrass species manage to survive in relatively wet climates, but most other members of the genus are adapted to arid lands. Many survive in areas with less than 6 inches of annual precipitation, and most are capable of surviving in sandy soils. All beargrasses store water in their leaves to help them survive during extended droughts.

Southwestern Beargrasses

Several beargrasses are popular ornamentals, including a few California natives.

Parry nolina (Nolina parryii) is a popular ornamental that produces yellow to cream flowers in the spring. In some cases, the flower stalk of these attractive plants can reach 10 feet in height. Native to southern California, Parry nolina is one of the most desirable plants for those living in the Los Angeles or San Diego areas.

Palmilla– also called sacahuista – is one of the most popular beargrasses for ornamental plantings; many homeowners employ them as grass substitutes. Palmillas live for a very long time, and often produce multiple heads after several decades of life. When this occurs, each head typically emerges from a central “trunk.”

In contrast to several other species within the genus, which are relatively common and have respectable natural ranges, dehesa nolina (Nolina interrata) is a rare plant with a restricted range, measuring about 6 square miles in size. There are less than a dozen places that the plants grow, all of which are basically found in an area between San Diego County and the Baha California border.

Chaparral beargrass (Nolina cismontana) was once considered a subspecies of Parry nolina, but it has recently been elevated to the level of full species. As indicated by the species’ common name, they are most common in the chaparral habitats of the Los Angeles and San Diego areas, but they also grow in coastal sage scrub habitats.

Floridian Beargrasses

Two Nolina species – Florida (Nolina atopocarpa) and Britton’s beargrass (Nolina brittoniana) — inhabit Florida, but both are currently very rare in the wild. In fact, both are protected in their home state and listed as endangered. Britton’s beargrass is in particular peril, and authorities have only documented 72 distinct populations. Unfortunately, those remaining populations exhibit rather limited genetic diversity, and clones may make up a large percentage of the current species.

The two species appear to be disappearing for similar reasons, namely habitat destruction and fire suppression. Both species are tolerant of wildfires, and they may actually depend on periodic fires for the continued success of the species; however, there is also some evidence that suggests they may persist for long periods of time without fire.  More research is required to tease apart the relationship between these plants and wildfire.

Cordyline_australis_Hinewai_New_Zealand

Trees of the Genus Cordyline: Cabbage Trees and Lily Trees

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About 15 woody plant species form the genus Cordyline. While botanists and horticulturists typically refer to the plants by their scientific names, laypersons often use names like cabbage trees, lily trees, or ti trees to refer to members of this genus.

Restricted to the Southern Hemisphere, most forms are native to Australia and the Southeast Asian archipelago. However, one species – Cordyline sellowiana — is instead native to Brazil and Bolivia. Some species have become established outside of their native range, such as the good luck plant (Cordylinefruticosa), which now grows in Hawaii.

Members of the genus are all monocots, meaning that they have parallel leaf veins (as grasses, lilies and true palms do) and their seeds bear only a single embryonic leaf, or cotyledon. Some species exhibit a distinctly tree-like growth habit, although a few members are better described as shrubs. None grows very tall; the largest individuals of the largest species rarely eclipse 15 feet in height.

Habitat Preferences

Most Cordyline trees are adapted for damp habitats. For example, Cordyline rubra – often called the palm lily in its native Australia – grows throughout the rainforests and mesic eucalyptus forests of the east coast. Similarly, palm lilies (Cordyline cannifolia) and broad-leaved palm lilies (Cordyline petiolaris) are also adapted to living under damp forest canopies, while narrow-leaved palm lilies (Cordyline congesta) typically grow near the edges of rainforests.

However, a few forms can adapt to drier habitats. Mountain cabbage trees (Cordyline indivisa) are most comfortable in damp forests, but they extend into the drier surrounding regions of their New Zealand homeland. At the other end of the spectrum, Three King cabbage trees (Cordyline obtecta) are more common in dry, sunny areas, and they fail to thrive in damp soil. The tiny dwarf cabbage tree (Cordyline pumilio) – which grows more like a sedge-like shrub than a tree –grows in drier scrublands and open-canopied forests.

Cultivation and Horticultural Use

Several members of the Cordyline genus appear in horticultural markets. Most are rather hardy species that require relatively little care. However, these plants are adapted to warm climates; few – if any – of these species tolerate frost. Horticulturists have produced cultivars of several members of the genus, including three King cabbage trees and good luck trees.

Broad-leaved palm lilies are common houseplants, although they also grow well in semi-shaded gardens with ample soil moisture. By contrast, the narrow-leaved palm lily (Cordyline stricta), which is one of the largest members of the group, is primarily used outdoors in screening applications. Narrow-leaved palm lilies are well suited for growing indoors or outdoors, as they adapt well to most growing conditions.

Food for Thought

Some species produce starchy rhizomes, which humans have used as a food source for thousands of years. The Maori people would cook the rhizomes to extract the sugar from them, while some Hawaiians ferment the rhizomes to produce a liquor. The leaves of the trees and shrubs were also used to thatch roofs or make clothing.

Many of the species produce attractive berries that vary from black to blue to red in color. These fruits not only provide aesthetic benefits, but they also serve as a food source for songbirds. Additionally, several of the species play a role in the lifecycles of local caterpillars.

Furcraea Plants

Furcraea Plants

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Native to Central and South America, the plants of the genus Furcraea are popular and interesting ornamental succulents. However, these plants – which go by an incredible array of names in nurseries and garden centers – are not only important to homeowners and landscapers; they play a large role in the lives of rural communities that have benefited from these plants for hundreds of years.

Classification and Description

Most of the species within the genus exhibit similar tendencies and needs. Each is a succulent that is well adapted to arid regions. Most of the species look like an inordinately large tuft of grass, but they are actually members of the asparagus family, and not terribly close to the grasses.

However, Furcraea species are closely related to a better-known group of succulents – the agave plants (genus Agave). In fact, Furcraea plants superficially resemble agaves, and they are often mistaken for them. The primary difference between the two groups involves the flowers: Agaves have thread-like filaments, while Furcraea plants have thicker filaments. Like many agaves, most fique plants are monocarpic, meaning they only bloom once before dying.

Despite the fact that most of these plants are small and remain less than 6 to 8 feet in height, Furcraea macdougalii possesses a tree-like trunk, which allows it to reach 20 feet in height. Many produce tall branch-like flowers that rise high above the plant’s leaves. One species – Furcraea longaeva — produces flowers that may rise up to 40 feet above the ground.

Ecology and Community

Fique plants tend to grow well in disturbed areas, as they appreciate abundant sunshine and require relatively little water. Many botanists consider them commensal organisms, as they clearly benefit from living in close proximity to humans. Additionally, these plants are able to thrive in areas with very little soil. This combination of traits has made fique plants valuable for many erosion-control projects.

Unfortunately, once introduced to new areas, these plants often become invasive and outcompete members of the local plant community. Fique plants are already threatening the survival of a few bromeliads in Brazil and a rare orchid species in Cape Verde.

The Resources of Fique Plants

Indigenous peoples of Central and South America call the 20 to 25 living members of the genus Furcraea a variety of different names, including fique, cabuyo, pita, and coquiza. Most of these names refer to the strong fibers present in the plants’ leaves.

These fibers have been harvested from the leaves for hundreds of years, being used to craft bags, roofs, cordage and a number of other goods. The plants remain an important resource in the modern world, and extracts of the leaves are used to create paper, soaps and fertilizers. Some even use the fibers to create an alcoholic drink.

Cultivation

Fique plants grow well outdoors, but many species also make good houseplants. A number of cultivars are sold commercially.

Many of the plants in this genus have exceptionally sharp spines; additionally, the terminal tip of the leaves is usually sharp enough to pierce human skin with ease. Accordingly, caution is warranted when planting these shrubs as ornamentals. They should be kept away from areas in which children or pets may play. It is generally wise to plant the larger varieties in open spaces with little foot traffic.

Maidenhair Trees

Maidenhair Trees

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Blessed with an impressive form, a hardy nature and unique leaves, maidenhair trees (Gingko biloba) are as attractive as they are interesting. With evolutionary roots extending deep into geological time, these leftovers of an ancient world have proven to be resilient survivors, who are even capable to thriving in 21st Century urban habitats.

Description

Though their branches often develop irregularly, maidenhairs typically achieve an aesthetically pleasing form. Maidenhair trees become quite large with age, sometimes surpassing 120 feet in height.

The distinctive bi-lobed leaves of maidenhair trees make them hard to mistake them for anything else. In fact, their specific epithet – biloba – means two-lobes (the name maidenhair refers to the species’ superficial resemblance to maidenhair ferns of the genus Adiantum).  As deciduous trees, maidenhairs shed their entire canopy each winter. However, before dropping to the ground, the leaves turn a beautiful shade of gold. Given their typically picturesque growth form, large specimens can be absolutely breathtaking in the autumn.

Maidenhairs are dioecious trees, meaning that individuals are either male or female. Female plants produce copious amounts of seeds that fall to the ground in the late fall or early winter. These seeds are covered with a foul-smelling seed coat, which many people find highly objectionable. The males produce no foul-smelling seeds, but they produce highly allergenic pollen.

Classification

As evidenced by their placement in the tree of life, maidenhair trees are some of the most unique organisms on the planet. Botanists consider maidenhair trees (Gingko biloba) to be the only living descendants of an entire phylum of plants.

To put this into some context, consider that every flowering plant in the world – from sunflower to redwood — is classified in the phylum Anthophyta. Scientists only recognize nine such groups (phyla) of living plants. Conifers form their own phylum, as do all ferns, horsetails, cycads, club mosses, gnetophyes and whisk ferns. And, as we said at the outset, maidenhair trees form their own phylum, called Gingkophyta.

Evolutionary Path

Maidenhairs had evolved by about 200 million years ago, and these ancient specimens strongly resemble the living species. Accordingly, many biologists call them “living fossils,” as they are living remnants of an ancient world. While some of the oldest maidenhair fossils exhibit a different form of seed attachment than living specimens do, those from about 65 million years ago are virtually identical to the modern form.

Culture, Cultivation and Cuisine

Maidenhair trees have played an important role in human culture, although this history only dates back about 1,000 years. People have grown maidenhair trees ornamentally for much of this time and harvested the seeds as a food source and for use in traditional medicine. Maidenhair trees are also popular subjects for the practice of bonsai.

Formerly found all over the globe, maidenhairs had virtually disappeared by about 2 million years ago. But before they could disappear forever, humans eventually found and cultivated some of these scattered survivors, thereby allowing the trees to be widely available in the modern world. The only known wild populations of the trees currently grow in a few Chinese localities.

Maidenhairs prefer forested sites, with well-drained, acidic soils, but they are highly adaptable trees that can live in a variety of habitats – including urban areas. Because they tolerate the indignities of city living, maidenhairs have become popular street trees, commonly planted throughout Europe, North America and Asia. Though they rarely escape cultivation in North America or Europe, they often become naturalized in parts of Asia.

Maple Tree

Maple Trees

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Maples (Acer ssp.) are some of the most beautiful and familiar trees in the world. In most places, they are an inescapable component of the natural world.

Maples grow in parks and backyards across the globe, provide delicious sap to coat waffles and yield the wood used to make furniture, floors, guitars and baseball bats.

But more than that, maples play important roles in almost every forest which they help to comprise; providing shelter, food and a yearly tithe to the leaf litter below.

Description

Maples are small to large trees, averaging less than 10 feet in height in some species to well over 100 feet for some others. Although the leaves, growth form, size and environmental preferences vary from one species to the next, most maples have a set of common characteristics. For example, all maples bear alternately arranged leaves, most of which feature palmate leaf veins.

Most maples are monoecious trees, meaning that most individuals bear both male and female flowers. The flowers typically appear early, often before the leaves have erupted. Maple flowers are small, but because the trees tend to produce so many flowers, the overall look of a blooming maple is often quite striking. A short time after flowering, maples produce double-seeds called samaras. These are the familiar “helicopters” seen falling slowly from the trees and littering the sidewalks below.

Diversity

Botanists recognize between 120 and 130 extant maple species. Some are widespread and common, while others are rare or even endangered. Most species live in the Northern Hemisphere; they are best represented in Asia, but they are also native to North America, Europe and North Africa.

A few of the noteworthy species include:

Native to much of Eastern Europe and Western Asia, Norway maples (Acer platanoides) are one of the most widely planted maple species in the world, although they are now regarded as invasive species in some locations. Norway maples rapidly colonize open areas, and once established they tend to inhibit the growth of nearby plants.

Box elders (Acer negundo) are weedy, short-lived maples, who are noteworthy for their ash-like leaves. In fact, because of their pinnately compound leaves, box elders are occasionally called ash-leaf maples. Although primarily confined to the eastern United States, box elders also grow in portions of northern California. Box elders are one of the few maple species to be dioecious and bear either male or female flowers, not both.

Japanese maples (Acer palmatum) are an important horticultural species, widely planted around the world. Japanese maples are widely prized for their elegant form, attractive foliage and small size, but they also require patience, as they are relatively slow growers. Horticulturists have produced more than 1,000 cultivars, with varying foliage and growth characteristics.

Sugar maples (Acer saccharum) are large maples, native to the northeastern United States (scattered individuals are found as far south as Georgia). Most commonly known for their contribution to the maple syrup industry, sugar maples are also attractive trees, planted as ornamentals. Sugar maples often form pure stands, and they represent an incredibly important resource for their resident wildlife.

Bigleaf maples (Acer macrophyllum) are one of the few maple species native to California. Like many California natives, bigleaf maples are rather drought tolerant after becoming established. Bigleaf maples are rather small trees, although large individuals may reach about 50 feet in height (a few records of 100-foot trees also exist, but such giants are rare). The species’ namesake leaves may reach up to 1 foot in diameter.

Native to Asia, paperbark maples (Acer griseum) bear a very attractive peeling bark. The bark is usually orange or orange-red in color, and provides a striking contrast in the winter, after the trees have shed their leaves. Paperbark maples are rather small trees, averaging about 20 to 30 feet in height.

Japanese Umbrella Pines

Japanese Umbrella Pines

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The Japanese umbrella pine (Sciadopitys verticillata) is the single described member of its genus, and – as its name suggests – it is a Japanese endemic. While a popular ornamental that is grown in many locations around the world, they are considered sacred in their native range.

Description

Japanese umbrella pines are unusual-looking trees that rarely solicit lukewarm opinions – as explained by the University of Florida Extension Service, “people either love this tree or won’t even look at it.” The whorled tufts of evergreen needles found at the end of the trees’ branches are said to resemble umbrellas, hence the species’ common name.

Interestingly, these umbrella-like needles carry out photosynthesis, but are not “true leaves.” Instead, the trees’ true leaves occur as scaly, twig-hugging structures. The foliage of these trees is often quite dense.

Although the cones are not produced for some time, those that eventually appear are relatively attractive. They are about 3 or 4 inches long and become quite plump at maturity.

The bark of Japanese umbrella trees is very attractive, having a rich-reddish-brown coloration. Its texture is often described as “fibrous” or “stringy.” Upon cutting into the wood, one immediately becomes aware of the wood’s distinctive, spicy fragrance.

Growth and Longevity

Japanese umbrella pines grow very slowly and take several decades to mature. Growing to about 90 feet in height in their native lands, most umbrella pines remain much smaller – typically less than 35 feet tall – when planted elsewhere.

The largest and likely oldest living specimen is located near a temple in the town of Nodagawa. The temple’s records indicate that the tree has been growing at the site for the last 700 years.

Evolutionary History

Although a member of the same order that contains living pines and spruces, the Japanese umbrella pine has no close relatives in the modern world. Japanese umbrella pines were originally classified within the family Cupressaaceae, but they have recently been moved to their own family, the Sciadoptiyaceae. This unusual conifer is a relic from an ancient time; researchers have collected fossil remains of these trees that are approximately 230 million years old. In fact, the species represents one of the oldest living conifer taxa in the world.

Extinct relatives of the species probably grew across vast expanses of North America, Europe and mainland Asia. Additionally, the trees probably played a more important ecological role in the Mesozoic Era than they do in the modern world.

Culture and Commercial Uses

Japanese umbrella trees are shade tolerant, but they grow best in partial to full sun. They grow best in USDA Hardiness Zones 4 and 5, although some authorities list them as hardy from Zones 3 through 7. Several cultivars of the species are available commercially, including a weeping form and a dwarf form, which only reaches about 10 feet in height.

While these trees require well-drained soil and have relatively modest water requirements, they are most common in humid cloud forests within their native range. These hardy trees are also resistant to most pests and pathogens, making them relatively low-maintenance trees. While these trees are most common among gardeners and landscapers, some bonsai practitioners utilize these attractive conifers.

The wood of Japanese umbrella pines is water-resistant; so many boat makers use it in ship construction.

Taxus_chinensis

Yew Trees

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Native to most of Europe and Asia, as well as northern Africa and North America, yew trees (Taxus spp.) are ancient species that have been associated with human culture for millennia.

Yew wood has been considered one of the finest materials for constructing longbows for centuries, but it has also been used to make spears and other tools throughout the ages.

Because they were thought to be a symbol of resurrection and immortality, yews were planted over graves by the ancient Celts. In the modern world, yews are primarily used as ornamental or shade trees, although they also provide the world with important medications.

Description

Yews are evergreen conifers whose flat, needle-like leaves twist around the stems to produce two flattened splays. Although most forms in the genus are very slow growing, some eventually reach heights of 120 feet or more.

Yews live relatively long lives; while 500 years is probably typical, a few living specimens have reached their 1,000th birthday. Nevertheless, the world’s oldest known specimen is much older than this – a tree growing in Perthshire, Scotland has reached approximately 5,000 years of age.

Yews are typically dioecious trees that feature male or female reproductive structures. Male yews produce small, round pollen cones, while females produce highly modified seed cones, which resemble red berries. Inside the fleshy red portion of the cone – known as the aril – lies a single seed.

Many birds and small mammals feed on yew cones, thereby serving as important agents of seed dispersal for the trees.

Familial Relations

The taxonomy of the living yews is not well resolved; although it is clear, they are all very closely related to each other.  Some authorities recognize about nine distinct species, while others consider the entire clan to be a single species, with many subspecies or geographic variants.

When regarded as a single species, the botanical name for the plant is Taxus baccata, with individual subspecies bearing names like the European (Taxus baccata baccata), Pacific (Taxus baccata brevifolia) or Irish (Taxus baccata fastigiata) yew. When recognized as different species, they simply become Taxus baccata, Taxus brevifolia and Taxus fastigiata.

Toxic Trees

Yews are noteworthy for their production of poisonous alkaloids, known as taxanes. Animals are occasionally found dead after having ingested yew tree leaves, twigs or seeds. Almost every part of a yew tree is toxic, including the bark, needles and seeds. The fruits, however, are edible and non-toxic.

Nevertheless, yew trees also produce very beneficial botanicals. The cancer drug paclitaxel was originally derived from the bark of yews, which led to the species’ precipitous decline in recent history. However, the drug is now primarily made via synthetic means, which has reduced the pressure on the trees.

Allergen-Inflaming Trees

The pollen of male yews is a potent allergen that causes acute symptoms in many people that come into contact with the trees. Interestingly, females do not produce allergenic pollen; whereas males earn a 10 out of 10 rating on the OPALS allergy scale, females are only rated as a 1. In fact, female trees collect some of the pollen produced by the males, thereby improving the air quality.

Cycas

Sago Cycad and Their Relatives

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Trees of the genus Cycas are primitive gymnosperms that superficially resemble palm trees. However, they are quite distinct from true palms, and form an entirely different lineage.

Description and Identification

Cycas trees – like most other members of the class Cycadopsida – feature a ring of pinnately compound (feather-like) leaves attached to the top of the trunk. You can further recognize members of the genus by noting the prominent mid-ribs of the leaflets and lack of any obvious secondary veins.

Like all other cycads, trees of the genus Cycas are dioecious, with distinct male and female plants. In both cases, the cones lie at the top of the trunk and emerge from the center of the leaf ring.

While some members of the genus feature round, subterranean trunks and are essentially shrub-like, others have tapering, tree-like trunks that grow aboveground. Most cycads feature relatively shallow root systems and grow very slowly. The majority of species remain rather small, with the largest specimens reaching perhaps 35 to 40 feet in height.

Relatives and Relationships

Between 90 and 115 species comprise the genus Cycas (the only genus in the family Cycadaceae), making it one of the largest lineages in the class Cycadopsida. Commonly known as the cycads, the ancestor of this group of species is thought to be the sister lineage to the other families in the class.

Cycads are ancient species that were found across most of the world by the beginning of the Triassic period. In fact, the entire Mesozoic era (which spanned from approximately 225 million years ago to 65 million years ago), is often called the “Age of the Cycads,” because of the plants’ dominance in these ecosystems. According to the University of California, Museum of Paleontology, cycads represented one-fifth of the world’s flora during much of the Triassic and Jurassic periods.

Habitats and Geography

Cycas trees are confined to the Old World. They are found from Japan, west to Africa and Madagascar, and south as far as northern Australia. As a group, the trees inhabit a variety of landscapes; some forms grow in tropical rainforests, while others grow along rocky escarpments.

Some species, for example, Cycas circinalis are well adapted to living along shorelines. The seeds of these trees are buoyant and capable of lasting extended periods of time floating through the ocean, until they eventually wash up in a habitable location.

Culture and Uses

One of the most commonly cultivated species is the so-called sago palm (Cycas revoluta). It prefers full sun, but some people succeed in growing them indoors. Because they remain relatively small, they are often planted in restricted spaces. If provided with a suitably large vessel, sago palms often thrive when grown in a container.

Several indigenous cultures throughout the range of these plants collect and eat the trees’ seeds as a food source, and some harvest starch – called sago — from the stems. However, neurotoxins are found throughout many different portions of the plants; if consumed, the poisons can cause serious disease or death. Accordingly, most people who eat the seeds or sago attempt to leach out the toxins with copious amounts of water.