Answer: Please find answers in explanation column.
Step-by-step explanation:
Our Causiana tree is a poem of 5 Stanzas and 55 lines by Toru Dutt who described her childhood memories in India centering about a tree, The Casuarina tree which she expressed her love for it .
What are the birds that sing throughout the day?
---- The birds that sing all day are the Kokilas as we can see from Stanza two , Line 7 which is
"And far and near kokilas hail the day;"
Kokila is a type of Asian cuckoo bird called the Asian Koel found mostly in India , China, and Southeast of Asia.
How do we know the water-lilies are white?
We know the water lilies are white because The writer compared the water-lilies by the hoar tree to gathered snow. and we know that Snow is white in colour. This we can see also in Stanza 2, but line 11.
"The water-lilies spring, like snow enmassed."