Salomonia cantoniensis（齒果草 ● Salomonia）

Salomonia cantoniensis is a annual herb species that is widespread and common in Hong Kong. Populations of the plant usually occupy relatively dryer habitats in shrublands. The species is most common in sunny habitats. I have observed populations growing at roadsides and open habitats near country trails. This species is distinguished from the other similar species in the genus, S. ciliata（橢圓葉齒果草）, by its winged stems. S. cantoniensis bears purplish red flowers in the summer and capsules with a denticulate surface. The structure of the capsule makes me wonder what evolutionary advantage does a denticulate  surface have. My guess is that although the plant may depend on wind or gravity to disperse its seeds, the denticulate surface can facilitate dispersion by animal fur or feathers so that the seeds can be transported to a further location once in a while.

Among a hike in NT east, I discovered  a population which bears white flowers instead of the usual purplish red. This phenomenon is not described in Flora of Hong Kong and some other sources. The unusual colour is probably due to genetic mutation or a recessive gene expression. The photos below are taken in NT east in summer.

Population with white flowers

White flowers with no purple pigment

Leaves and stem of the white-flowering population. Stems are winged

A normal spike with purplish flowers

Purple flowers, the structure below are the capsules 

Winged stem of the purple-flowering population

Rhododendron championiae（毛葉杜鵑 ● Champion's rhododendron）

Rhododendron championiae is a shrub or small tree that has restricted distribution in Hong Kong. According to Flora of Hong Kong, the species can only be found in limited localities including Tai O, Ma On Shan, and Victoria Peak. Personally, I've seen the population growing in Tai O and the one on Ma On Shan. The species seems to be growing in shrublands on steep slopes. The species is characterized by its glandular hairs growing on leaves and buds, an adaptation probably used to save water and prevent insects from eating the tissues of the plant. In spring, white flowers with yellowish dots and occasionally having a touch of pink color emerge. The fruit of the plant is a capsule that holds the seeds before they are distributed by anemochory like other Rhododendron spp.. The photos below show withering flowers of R. championiae in Tai O (I was a little too late).

Flowers

New leaves

Old leaves (crowed towards the apex, in a whole like arrangement)

Flowers

Flowers

Flowers

The whole population on the slope

Utricularia caerulea （短梗挖耳草 ● Blue bladderwort）

Utricularia caerulea is a small carnivorous plant that grows in wet environments. The species is particularly common on wet rocks near streams, commonly found with other Utricularia spp.. The ecological niche of the species is somewhat similar to that of U. bifida. Both plants are usually not submerged and growing in relatively drier habitats near streams. U. caerulea bears flowers in late summer, autumn, and winter. The species has two different flower colours, white and purple. Both variations are quite common in Hong Kong. I found populations of white flowers in a few sites in Sai Kung and on Lamma Island. While I observed populations with purple flowers in Tai Lam, Hong Kong Island and in another site on Lamma Island. Surprisingly, the two varieties doesn't mix together. The two sites on Lamma Island are only a few kilometers apart but plants in a site is either purple or white, not both. It may suggest that different populations rarely cross pollinate, and the seeds do not travel far enough to another stream. Below are some photos I took in various sites.

Purple flowers

Fruits

Purple flowers

Purple flowers

Population with purple flowers only

White flower

Population with only white flowers

The damp soil in its habitat

Utricularia bifida（挖耳草/割雞芒 ● Small yellow bladderwort）

Utricularia bifida is a small carnivorous herb growing in wet places and marshes, especially in wet rocks near streams. It is the most common species in the genus, widespread in different areas. Usually, the species shares its habitat with other Utricularia spp. such as  U. uliginosa (濕地挖耳草）, U. caerulea（短梗挖耳草）,and U. striatula（圓葉挖耳草）. However, the species seems to be able to tolerate slightly drier habitats when compared with other Utricularia spp.. I once seen a flowering, healthy population growing on rocks that almost dried up and under direct sunlight, with no other Utricularia spp. growing nearby. Like other species in the genus, the plant produces traps on leaves, roots, and other submerged structure. I heard that the traps use water pressure difference to suck small aquatic organisms in, but the traps are too small for me to observe. U. bifida is characterized by its yellowish flowers. Here are some pictures taken on an outlying island, populations are also seen in streams all over Hong Kong.

Yellowish flower

Leaves (the small, long ones)