The Cactus is one of the greatest critiques of egotism and hypocritical conceit by O’Henry. The basic storyline is simple. Trysdale, a young man, noble, wealthy and cultured, realizes that his girl friend is excessively devoted to him and sort of worships him. She showers him with all sorts of superlative appellations and Trysdale very fondly accepts them, as naturally as the desert sand soaks up rain. He takes her for granted, since the guiding principle of his life is vanity. ‘She had always insisted on placing him upon a pedestal, and he had accepted her homage with royal dignity’. Ultimately the day comes when Trysdale proposes to her. He is sure that she would be too eager to accept him readily. She showed all kinds of emotional jubilation and her body language too had been one of eager consent.’ How glad, how shy, how tremulous she was….(There was) unmistakable consent in her eyes’, but it is her feminine modesty and coyness that results in her statement that she would send her answer the day after. The next day, Trysdale desperately awaited her reply, and his notion of himself as ‘the indulgent, confident victor’ was being deeply hurt. However, she sent through her groom a cactus plant with a tag ‘bearing a barbarous foreign or botanical name’ which he simply did not care for. Trysdale had taken the cactus as a mark of refusal or betrayal.

The story is set in Trysdale’s drawing room after the marriage ceremony of this girl was over and the scent of the huge bunches of flowers piled in the church was still haunting him. He was filled with bitterness and chagrin, trying to ruminate upon the reason for his loss and how lovingly the girl had given her to the bridegroom in a public ceremony within the church. Trysdale was deeply distressed and looked unhappy. With him, at the present moment, was his friend who happens to be the brother of the bride, who coincidentally finds the tag on the cactus and says that it was a common cactus in South America where he lived, and that the word on the tag was not a biological name, but a common Spanish word with which the plant is called. That word ‘Ventomarme’ means in Spanish “come and take me”. Trysdale now realizes his fault at ignoring the tag and the cactus sent by his proposed girl friend and instead expecting her assent in the way he expected her to give it. In his vanity Trysdale had ignored the call of bliss in his life and it was now too late to realize it.

The crux of the matter lies in a short interface between the two a long time ago. In those days of courtship or rather worship on the part of the girl, she had once asked him why he had not revealed to her his great knowledge of the Spanish language. This had been reported to her by a foolish admirer of Trysdale, one captain Carruthers. Trysdale knew very well that this was not true, that all his Spanish was mugged up from hackneyed Spanish phrases which he often learnt from the dictionaries and used them only to show off. But Trysdale was too proud to tell her the truth. She, therefore, was under the impression that he was a master of Spanish and had, therefore, very romantically assented to his proposal in the Spanish language which he had failed to comprehend, thus giving her a false impression of being rejected by him.

O’Henry suggests through "The Cactus" that love demands truth and openness of heart. Hypocrisy and pride are the anathema to the world of love.

As is typical of the writings of O. Henry, "The Cactus" has a surprise ending.  This surprise results because of the character trait about which Trysdale berates himself:  "his fatuous and tardily mourned egoism."  Having returned from the wedding of the beautiful young woman whom he had assumed he would marry, Trysdale rues his vanity and conceit.  But, the irony is that he does not fully understand how this very vanity and conceit prevented his marriage.  For, as Trysdale searches in his memory for where he erred, he remembers how the young woman always looked up "so childlike and worshipful," but she was always modest. 

Recalling the night on which he had proposed to the beautiful woman to marry him, she had asked him about keeping quiet his knowledge of Spanish since Captain Caruthers had told her that he is fluent. Because "the incense of her admiration" was so sweet and flattering, he allowed her to retain the assumption that he knows the language.  Yet, Trysdale has thought no more of this question of hers.  Instead, he remembers how she seemed a "snared bird" that night.  Yet, she sent no word as she had promised; and, when he saw her two nights later, she seemed "wondering, eager."  Courteous, but adamantly quiet, he awaited her explanation; she gave no reply, but became cold.

Then, the voice of the other man in the room intrudes his reverie, asking him what is wrong and suggesting they have a drink. Rather distractedly, the friend sees the cactus on Trysdale's table and asks him where he got it. 

"A present," said Trysdale, "from a friend. Kinow the species?"

"Here's the name on the tag," his friend replies.  "Know any Spanish, Trysdale?"

"No," said Trysdale, with the bitter wraith of a smile--"Is it Spanish?" 

Now, Trysdale suspects that his egoism at not admitting to not having knowledge of Spanish has been a true mistake.

Yes, explains his friend.  He tells Trysdale the Spanish name is Ventomarme, which means "Come and take me" in English.  Ironically, Trysdale's  his pretense and egoism have been his nemesis. However, while this trick ending of O. Henry's is pathetic, it is not tragic.