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)