Saturday, February 15, 2014

Ranunculus sceleratus(石龍芮 ● Celery-leaved crowfoot)

   Among many wetland plants, Ranunculus sceleratus is a rather uncommon one. It is a beautiful annual herb that grows in spring. The species is suited to grow in relatively colder days.

   In suitable habitats such as wet farmlands in Yuen Long, I've seen the plant growing to almost half a meter tall. I found a population of the species very close to my home and used a great deal of time to observe it. Unfortunately, that population grows in relatively dry urban environment and is often removed by gardeners, so the plants growing there are relatively short, most of the plants found there mature and start to flower when they are just a few cm tall.

   The plant has two kinds of leafs. The leaves in the lower portion of the plant is 3-partile and relatively broad. For cauline leaves, the higher the position of the leaf, the less divided it is. This adaptation is used when the plant grows in shallow water. The basal leaves floats while the cauline ones does not touch the water. Yellowish flowers could be found in the upper portion of the plant. The receptacles in the flower gets longer and longer as the flowers develop. At last, petals fall and the receptacles develop into an aggregate fruit. I'm quite curious of the dispersion method the fruits use. Since the plant could be dispersed to places far from water, it is unlikely that the plant uses water or aquatic animals to disperse its seeds. The shape of the fruit suggests that it does not rely on wind dispersal (anemochory). I suspect that the plant relies on birds to disperse its seeds but the color doesn't seem to be attractive or attention grabbing at all so it is kind of strange.

  The following pictures are taken in the population found in the urban area in spring, probably originally entered the system through the soil.
Plant in urban environment

Basal leaf

Leaf in the middle

Cauline leaf, not lobed,

Yellowish flower

Lateral view, flower

Fruit, greenish

Friday, February 14, 2014

Goodyera procera(高斑葉蘭 ● Tall rattlesnake-plantain)

There are more than one hundred species of orchids in Hong Kong. Most of these species are very rare and some even went locally extinct. Goodyera procera is one of the exceptions, it is locally common and could be found in many streams or wet places. Maybe since the species doesn't have large flowers nor ornamental value, it escaped from illegal orchid collection and remained widely distributed. Flora of Hong Kong described the ecology of the species as growing in 'earth pockets on rocks in stream bed'. This is indeed a very accurate description of where the species could be found. G. procera does not have a psuedobulb nor does it have thickened roots. It has an erect stem and does not possess a creeping rhizome. Maybe since the species is found near streams, water is ample and the plant does not have to store up water in root tissues. Small white flowers clustered on a terminal raceme could be found in spring (Flora of Hong Kong: Mar. to Apr.) The following pictures are taken in April in Ma On Shan Country Park.
Population

Growing in earth pockets of streams

Leaves

Abaxial surface of leafe

Terminal raceme

Flowers, showing typical orchid flower structure

Flowers
Base of plants with roots that are not thickened, stems upright

Sunday, February 9, 2014

Rhododendron hongkongense(香港杜鵑 ● Hong Kong azalea)

  Rhododendron hongkongense is a shrub or small tree species with very restricted distribution in Hong Kong. Due to its restricted distribution, the plant included in the book of Rare and Precious Plants in Hong Kong.

  The largest population in Hong Kong is the population growing in the Ma On Shan area. Claiming that the population is shrinking, AFCD (Agriculture, Fisheries and Conservation Department) has started a scheme to protect the species. The department removes other more common plants such as Polyspora axillaris(大頭茶).The scheme received quite a lot of opposition from the public (including myself) mainly due to two reasons. Firstly, although P. axillaris is a common species, it is a host to Korthalsella japonica(栗寄生), a obligate stem hemiparasite that is even rarer than R. hongkongense in Hong Kong. Secondly, AFCD did not remove the poisonous nails after it is used on the plant so the poison could possibly spread out in the ecosystem.

  R. hongkongense bears white flowers in late spring. The white flowers are followed by bright red to purple new shoots which stand out in the forest.

  According to Flora of Hong Kong, the species' taxonomic status is still quite unclear and more evidence is needed to separate the species completely from R. ovatum and R. bachii.

  The photos below are taken in Ma On Shan in spring.
Fallen flowers

Fallen flowers, purple spots might be used to guide bees towards nectar

new shoots

leaf

new shoots

white flowers

flowering plant in the forest really stands out


flowers