The stem of Dwarf tree fern is upright, which looks like a tree trunk. Some ferns also have the same stem so they are called "tree ferns". The most famous tree fern should be Scaly Tree-fern (Cyathea lepifera). Despite its name, a "tree fern" is actually a herbaceous plant. Its stem is different from that of woody plants. It has no cambium, does not grow thicker, does not form annual rings, and is hollow, with aerial roots covering the stem outside. The stem of Scaly Tree-fern can be up to 20 meters, and the leaves can be up to 3 meters. It is a tall tree fern. The plant height of Dwarf tree fern is only about 1 meter, and the leaves are about 40 to 80 cm long. It is considered a small tree fern and hence its common name.
Dwarf tree fern
（2023.2.22 Taiwan）
About Blechnum gibbum
| ◆ | Classification: Genus Blechnum, Family Blechnaceae | |
| ◆ | Scientific name: Blechnum gibbum | |
| ◆ | Common Name: Dwarf tree fern, Silver lady fern, Miniature tree fern | |
| ◆ | Chinese name: 富貴蕨、肋骨蕨、美人蕨、巴西肋骨蕨、巴西烏毛蕨、樹烏毛蕨、疣莖烏毛蕨、駝背烏毛蕨、凸起烏毛蕨 | |
| ◆ | Origin: South pacific islands, Fiji, Hawaii, New Caledonia and the islands of the South Pacific | |
| ◆ | Growth environment: Prefers warm, semi-shade and high humidity environment; often grown as a garden landscape plant |
|
| ◆ | Growth habit: Perennial herbaceous plant, terrestrial | |
| ◆ | Hight: up to 1 meter | |
| ◆ | Rhizome: Erect, up to 5 to 10 cm in diameter, hollow | |
| ◆ | Frond | |
| 》 | Clustered on top of stem | |
| 》 | Stipe: Short, about 5 to 15 cm long | |
| 》 | Blade: →Unipinnately compound leaf →Oval lanceolate →40-80 cm long, 15-40 cm broad, widest in upper middle →Nearly coriaceous |
|
| 》 |
Pinnae →Narrow lanceolate →About 10-25 cm long, 0.6-1 cm broad, the lower the smaller →Sessile, connates with rachis at base and extends down along the rachis →Margin entire or serrated, undulate |
|
| 》 | Veins free, single or binary forked; rarely reticulate vein, the areolae without included veinlets |
|
| ◆ | Sori | |
| 》 | Sori linear, parallel to both sides of the middle rib of the pinnae | |
| 》 | Indusium linear, open to the middle rib | |
Dwarf tree fern is native to South pacific islands, Fiji, Hawaii, New Caledonia and the islands of the South Pacific and is widely cultivated as a gardening landscape plant all over the world.
Dwarf tree fern
（2016.5.24 Taiwan）
It is in the family Blechnaceae and looks like Brainea insignis which is in the same family.
Dwarf tree fern
（2023.2.22 Taiwan）
It also looks like Cycas revoluta which is in the family Cycadaceae.
Dwarf tree fern
（2014.11.7 Taiwan）
It is a perennial herbaceous fern, terrestrial, and its plant height can reach about 1 meter.
Dwarf tree fern
（2014.11.7 Taiwan）
Some ferns have upright erect stem, hollow and covering with aerial roots, and look like a trunk. We call this type of ferns as "tree fern". Although tree ferns are called "tree", they are still herbaceous plants. Their stems are different from the stems of the woody plants. There is no formation layer, so it will not grow thicker and thicker, and it will not form an annual wheel. Dwarf tree fern is a tree fern, but its height is only about 1 meter, and the trunk diameter is only about 5 to 10 cm. It is considered a small tree fern.
Compare the above and below photos. The above one is taken in 2014 while the below one is taken in 2023. The location and ferns are the same. At first glance, they seem to be not much different except the leaves in 2023 are larger and more, but the height does not seem to be much higher, Why?
Compare the above and below photos. The above one is taken in 2014 while the below one is taken in 2023. The location and ferns are the same. At first glance, they seem to be not much different except the leaves in 2023 are larger and more, but the height does not seem to be much higher, Why?
Dwarf tree fern
（2023.2.22 Taiwan）
Take a closer look at the plants in 2023, and you will find that the stems of these Dwarf tree fern have fallen down, so the lower half lies on the ground.
Rhizome of Dwarf tree fern
（2023.2.22 Taiwan）
The stems of tree ferns have no cambium, do not thicken with age, and are hollow, so they are far less supportive than woody stems.
When the stem grows taller and taller and the leaves on it are getting larger and more numerous, then the stem will gradually topple over because they are top-heavy and unable to support them and during this period they even may be hit by strong winds. Finally the stem lies on the ground in a crawling shape and then grows upwards on apex again.
Rhizome of Dwarf tree fern
（2023.2.22 Taiwan）
In the photo below, the plant in the front looks as if it has fallen down three times in different directions. In this garden, the upright part of stems of Dwarf tree fern are only about 30 to 40 cm.
Rhizome of Dwarf tree fern
（2023.2.22 Taiwan）
There are aerial roots on the surface of the stem.
Rhizome of Dwarf tree fern
（2023.2.22 Taiwan）
Fronds are clustered on top of the stem.
Frond of dwarf tree fern
（2014.11.7 Taiwan）
Stipes are short, about 5 to 15 cm long.
Stipes of dwarf tree fern
（2023.2.22 Taiwan）
Blades are unipinnately compound, oval lanceolate, 40-80 cm long, 15-40 cm broad, widest in upper middle, nearly coriaceous.
Blade of Dwarf tree fern
（2023.2.22 Taiwan）
Fiddleheads of Dwarf tree fern.
Fiddleheads of Dwarf tree fern
（2023.2.22 Taiwan）
Fiddleheads of Dwarf tree fern.
Fiddleheads of Dwarf tree fern
（2023.2.22 Taiwan）
Pinnae are narrow lanceolate, about 10-25 cm long, 0.6-1 cm broad.
Pinnae of Dwarf tree fern
（2023.2.22 Taiwan）
The lower the pinnae, the smaller.
Pinnae of Dwarf tree fern
（2023.2.22 Taiwan）
The pinnae are sessile.
Pinnae of Dwarf tree fern
（2023.2.22 Taiwan）
The pinnae connates with rachis at base and extends down along the rachis.
Pinnae of Dwarf tree fern
（2023.2.22 Taiwan）
Pinnae margin is entire or serrated, undulate.
Pinnae of Dwarf tree fern (abaxial side)
（2023.2.22 Taiwan）
Veins are free, single or binary forked. Rarely there are reticulate veins and the areolae without included veinlets.
Veins of Dwarf tree fern
（2023.2.22 Taiwan）
Sori are linear.
Sori & indusium of Dwarf tree fern
（2023.2.22 Taiwan）
Sori grow parallel to both sides of the middle rib of the pinnae.
Sori & indusium of Dwarf tree fern
（2023.2.22 Taiwan）
Indusium are linear.
Sori & indusium of Dwarf tree fern
（2023.2.22 Taiwan）
Indusium open to the middle rib.
Sori & indusium of Dwarf tree fern
（2023.2.22 Taiwan）
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