Rubus hawaiensis
Encyclopedia
Rubus hawaiensis, also called the Ākala, is a species of Rubus
endemic to Hawaii
. It is found on the islands of Kauai
, Molokai
, Maui
, and Hawaii
in mesic to wet forest at elevations of 600–3070 m (1,968.5–10,072.2 ft). In most areas it is not very common, but in some places (such as the upper Koolau Gap in Haleakalā
and Laupāhoehoe Natural Area Reserve) it can be a dominant member of the understory vegetation. Although superficially similar to the other Hawaiian species, Rubus macraei
, the two are believed to be derived from separate dispersals to Hawaii.
R. hawaiensis is a deciduous
shrub
, typically growing as a clump of erect or (when longer) arching canes, 1.5–3 m (4.9–9.8 ft) long. The leaves
are compound, with three leaflets. The fruit
is red, large (up to 4 cm (1.6 in) long and 2.5 cm (0.984251968503937 in) wide), and edible but not often eaten, as it is sour and somewhat bitter.
Although frequently described as thornless (and often used as an example of loss of defenses in island plants), most plants do have thin thorns (which can make splinters and be quite painful) at least when small. As the cane grows the outer layer of bark usually sheds, taking the thorns with it. Interest in breeding thornless varieties of edible raspberries (possibly even with distantly related species since most Rubus readily hybridize) has led to the introduction of several species of continental Rubus species which have since escaped cultivation and become serious pests. These include the yellow Himalayan raspberry, Rubus ellipticus
, and the Florida prickly blackberry, Rubus penetrans. Both of these are odd choices for breeding for cultivation as they have small, poor-tasting fruit.
The presence of highly damaging alien Rubus species along with a native species has led to a debate on biological control. Specifically, whether an agent that might be able to control the alien species (which are highly invasive in native forest and crowd out native species) should be released even if it may have serious impacts on a native species, if the latter is (like the ākala) not part of a major evolutionary diversification and not a major part of most ecosystems. Some would argue that it is worth sacrificing a small component in order to save the whole ecosystem, while others say that humans should not be multiplying the damage they have already caused by introducing the aliens.
Rubus
Rubus is a large genus of flowering plants in the rose family, Rosaceae, subfamily Rosoideae. Raspberries, blackberries, and dewberries are common, widely distributed members of the genus. Most of these plants have woody stems with prickles like roses; spines, bristles, and gland-tipped hairs are...
endemic to Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
. It is found on the islands of Kauai
Kauai
Kauai or Kauai, known as Tauai in the ancient Kaua'i dialect, is geologically the oldest of the main Hawaiian Islands. With an area of , it is the fourth largest of the main islands in the Hawaiian archipelago, and the 21st largest island in the United States. Known also as the "Garden Isle",...
, Molokai
Molokai
Molokai or Molokai is an island in the Hawaiian archipelago. It is 38 by 10 miles in size with a land area of , making it the fifth largest of the main Hawaiian Islands and the 27th largest island in the United States. It lies east of Oahu across the 25-mile wide Kaiwi Channel and north of...
, Maui
Maui
The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...
, and Hawaii
Hawaii (island)
The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...
in mesic to wet forest at elevations of 600–3070 m (1,968.5–10,072.2 ft). In most areas it is not very common, but in some places (such as the upper Koolau Gap in Haleakalā
Haleakala
Haleakalā , or the East Maui Volcano, is a massive shield volcano that forms more than 75% of the Hawaiian Island of Maui. The western 25% of the island is formed by the West Maui Mountains.- History :...
and Laupāhoehoe Natural Area Reserve) it can be a dominant member of the understory vegetation. Although superficially similar to the other Hawaiian species, Rubus macraei
Rubus macraei
Rubus macraei, commonly known as Ākalakala, is a species of Rubus that is endemic to Hawaii. Although superficially similar to the other Hawaiian species, Rubus hawaiensis, the two are believed to be derived from separate colonizations of Hawaii. R...
, the two are believed to be derived from separate dispersals to Hawaii.
R. hawaiensis is a deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
, typically growing as a clump of erect or (when longer) arching canes, 1.5–3 m (4.9–9.8 ft) long. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are compound, with three leaflets. The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
is red, large (up to 4 cm (1.6 in) long and 2.5 cm (0.984251968503937 in) wide), and edible but not often eaten, as it is sour and somewhat bitter.
Although frequently described as thornless (and often used as an example of loss of defenses in island plants), most plants do have thin thorns (which can make splinters and be quite painful) at least when small. As the cane grows the outer layer of bark usually sheds, taking the thorns with it. Interest in breeding thornless varieties of edible raspberries (possibly even with distantly related species since most Rubus readily hybridize) has led to the introduction of several species of continental Rubus species which have since escaped cultivation and become serious pests. These include the yellow Himalayan raspberry, Rubus ellipticus
Rubus ellipticus
Rubus ellipticus commonly known as Yellow Himalayan raspberry is a thorny fruiting shrub that originates from South Asia.-Invasive species - 100 worst:...
, and the Florida prickly blackberry, Rubus penetrans. Both of these are odd choices for breeding for cultivation as they have small, poor-tasting fruit.
The presence of highly damaging alien Rubus species along with a native species has led to a debate on biological control. Specifically, whether an agent that might be able to control the alien species (which are highly invasive in native forest and crowd out native species) should be released even if it may have serious impacts on a native species, if the latter is (like the ākala) not part of a major evolutionary diversification and not a major part of most ecosystems. Some would argue that it is worth sacrificing a small component in order to save the whole ecosystem, while others say that humans should not be multiplying the damage they have already caused by introducing the aliens.
External links
- Hawaiian Native Plant Genera - Rubus Photographs of R. hawaiensis.