Katherine Mansfield’s story “Bliss” can be read as a satire on the artist-milieu of her time, combined with the subject of disloyality. But it also is full of symbols. To understand the complete meaning of the story, we have to interpret these symbols.
As Bertha Young, the protagonist, identifies herself with the pear tree, this symbol seems to be very important for our interpretation (especially of the last, mysterious sentence). In my opinion the pear tree stands for two aspects related to Bertha which might help us to get a deeper view on “Bliss”: her bisexuality and (far more relevant) her virginity.
Why is the pear tree a symbol for Bertha’s bisexuality?
Botanically a peat tree can be regarded as bisexual by nature because it is self-fertilizing. It has both female and male organs. But I also can verify my thesis according to text: When Bertha shows her garden to Pearl Fulton, this is a crucial moment of the story. Bertha is highly emotional in this scene because she forgets the world and the time around her and her thoughts are described emotively. The pear tree occurs in this scene in a remarkable way for it seems “to touch the rim of the round, silver moon”. We have to keep in mind that the pear tree symbolizes Bertha for she explicitly says that (p.123) and her dress resembles to the pear tree. The moon and its silver light are an important symbol, too. Therefore we need to find out its meaning. I suggest to interpret the moon in “Bliss” in a very classical way: The moon is an ancient symbol for the feminine principle in the world (as the sun stands for the masculine; cp. lat. luna, f., sol, m.). The cycle of the female sex hormone (i. e. menstruation) and the cycle of the moon are similar. So we can make a simple connection between the moon and female sexuality. Why is the moon so important in this story? Because Pearl is associated with the moon. She is dressed all in silver, she has “moonbeam fingers” (p.135) and Bertha compares her to the moonlight, thinking: “(...) the light of (...) [the] moon, silver as Miss Fulton”(p.129).
So when Betha gets the impression or imagination that the pear tree (herself) touches the moon (Pearl), it comes clear that Bertha adores her. She longs for physical fusion with Pearl. The pear tree touching the moon is a sexual picture. It is remarkable that the tree looks like a phallus for, to Bertha, it seems “to stretch up, to point, to quiver (...), to grow taller and taller”(p.131). This makes the sexual aspect of the tree even more obvious.
 cp. Helen Nebeker,“The pear tree: Sexual implications in Katherine Mansfield’s Bliss,” MFS 18 (1972/73): 546.
 Katherine Mansfield, „Bliss“ and other stories (London: Constable Publ., 1920) 116. All following page references in the text concern this edition.