Answer: The beautiful white flower is water lotus, Nelumbo, which comes from warmer climes. You could be lucky in central London and succeed in growing this, as long as the temperature does not fall below freezing at rooting level. High temperatures of around 25degC are needed to ripen the roots! Try growing it in a container and settle it into a pond in a barrel, in rich, heavy loam. You could then overwinter it in frost-free conditions such as a greenhouse if you have one.
Your other photo is the faded flower stem of Helicona, a tropical plant that comes in vibrant yellows, reds and oranges. Warm conditions all year round are needed - a conservatory with a minimum winter temperature of 15degC would be ideal, in filtered light.
You may prefer to enjoy both of these plants on visits to the tropics, or come back to one of the many tropical glasshouses open to us here, such as at Kew.
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