Do you know how to write some flower names in Japanese characters especially in Kanji symbols. The left side kanji "花(はな-hana, か-ka) " means flower, and some of flower names contain the letter of 花 (usually last of their names) when they are written in Japanese Kanji as you can see in the following flower name lists.
As you can see in the list. Cactus can be written "仙人掌" in Kanji but usually we prefer to use Katakana for writing Cactus, so サボテン is generally used in our daily life.
And I think we don't have specific Japanese name for Carnation so we write its name using Katakana like the below list.
The flower names "花", "桔梗", "桜", "菊", "皐月" and "菫" are often used as girls name in Japan. And even though "Ginger (生姜)" is often used as girl's name in English world, we rarely use "生姜" as girl's name in Japan.
The Kanji meaning of "鶏頭" is "head of chicken", so apparently the Japanese naming for this plant is similar to English naming.
Also the meaning of "朝顔" is "morning (朝) face (顔)". So the English naming and Japanese naming for this flower is very similar.
Flowering Crab Apple
Lily of the Valley