English ivy is a good example of both positive (leaves) and negative
phototropism (stems and roots). Negative phototropism of ivy stems allows
them to climb trees and buildings.
Partridgeberry (Mitchella repens), a native woodland wildflower in the
eastern USA, was once a popular Xmas decoration because of the
long-lasting red fruit. It was often placed in a glass container to make a
partridgeberry bowl, a type of terrarium. The fruit are edible.
The evergreen Christmas fern (Polystichum acrostichoides), an eastern USA
native, was once collected as a major cut foliage item for Xmas sales.
The Xmas rose (Helleborus niger) is valued because it blooms outdoors
around Xmas, however, it is poisonous and has been used medicinally.
Despite the name it may not always bloom at Xmas but can be forced indoors
to assure Xmas flowering.
Star of Bethlehem (Ornithogalum species) can be forced to bloom for Xmas
but they are poisonous. O. umbellatum blooms in the spring outdoors and is
often an escaped weed in the USA.
Ken Post (1949, Florist Crop Production and Marketing, New York: Orange
Judd) notes several popular Xmas potted plants. Coralberry (Ardisia
crenata) has long-lasting red fruit. It supposedly has nitrogen fixing
nodules in the margins of its leaves. Another Xmas plant that fixes
nitrogen is the bayberry (Myrica).
Other Xmas plants include the Xmas begonia (B. socotrana), cyclamen,
azalea, Xmas cactus, and kalanchoe, all valued for their flowers. Cyclamen
also has beautifully variegated leaves. The Xmas pepper (Capsicum annuum),
Jerusalem or Xmas cherry (Solanum pseudocapsicum), and False Jerusalem
Cherry or Xmas orange (Solanum capsicastrum) are valued for their colorful
fruit. Xmas pepper was bred from chili and cayenne peppers so fruit are
edible but hot. Jerusalem cherry fruit are poisonous. Christmas-cheer
(Sedum rubrotinctum) is a houseplant whose leaves turn red when exposed to
bright light. All but Xmas begonia are still popular.
Many plants have Xmas as part of their common name because the plant
blooms or fruits at Xmastime in its native habitat. For example, New
Zealand Xmas tree (Metrosideros excelsa) blooms in the USA during
June-July due to reversal of seasons in the Northern hemisphere.
Colonial Xmas tree decorations were often plant materials, such as
polished nuts, dried orange slices, apples, and the still popular strings
of popcorn and cranberries. Other popular Xmas decorations are bayberry
candles, candle holders made from logs, deer and other figures made of
woven branches, and pseudotopiary - potted English ivy trained on wire
frames to form wreathes, Xmas trees, etc.
Xmas wreathes, garlands, roping, and swags are made from just about any
evergreen tree or shrub including fir, yew, pine, arborvitae, juniper,
box, mountain laurel, rhododendron, littleleaf Japanese holly, Southern
magnolia, etc. Many berried shrubs are popular substitutes for holly, such
as pyracantha, Xmas berry (Heteromeles arbutifolia), and Xmasberry tree
(Schinus terebinthifolius). Because many people prune their landscape
evergreens for Xmas greens, proper pruning techniques and apical dominance
are appropriate topics.
Cone wreathes are also popular and can include more than just cones, such
as acorns, eucalyptus pods, milkweed pods, etc.
A popular Xmas gift is an amaryllis bulb (cultivars of Hippeastrum). In
the USA, the ChiaPet has become a popular novelty Xmas gift in recent
years. It consists of an unglazed ceramic animal or other figure filled
with water and covered with chia (Salvia hispanica) seeds which sprout to
give a "fur coat".
Frankincense and myrrh were plant gifts brought by the Three Wise Men.
They were also used by ancient Egyptians in mummification.
Xmas foods and spices of plant origin are numerous including peppermint
candy canes, cinnamon, nutmeg, fruit cakes, chocolate, citrus and apples
in Xmas stockings, and "chestnuts roasting on an open fire." A discussion
of chestnuts could include the devastation of the American chestnut caused
by human introduction of chestnut blight, an illustration of why we need
strict plant inspections and quarantines.
To discourage thieves who steal them for use as Xmas trees, landscape
evergreens are often sprayed with a chemical that makes them stink.
Living Xmas trees are sold balled and burlapped or in a container and can
be planted outdoors after the holidays. Norfolk Island pine (Araucaria
heterophylla) is a houseplant that makes a good Xmas tree. Outdoors it may
reach 60 meters. It is propagated by cuttings of erect shoots. Lateral
shoots are unsatisfactory because they are plagiotropic.
Although not biology, mistletoe and ivy have many interesting legends and
superstitions associated with them. See Lys, Claudia de. 1989. What's so
lucky about a four-leaf clover? New York: Bell.
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David R. Hershey
HOME: WORK:
Biology/Horticulture Department
6700 Belcrest Road #112 Prince George's Community College
Hyattsville, MD 20782-1398 Largo, MD 20772-2199
Email dh321 at pgstumail.pg.cc.md.us
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