1. An individual flowering dogwood is small and inconspicuous, with four greenish-yellow petals. Densely clustered in its center are about 20 tiny flowers in a round umbrella-shaped inflorescence, (which are) surrounded by four noticeable bracts that are white, pink or red in color.
2. An individual flowering dogwood is small and inconspicuous, with four greenish-yellow petals, in the center of which clustered twentyish tiny flowers in a round umbrella-shaped inflorescence, surrounded by four noticeable bracts that are white, pink or red in color.
An Individual flower of a flowering dogwood is relatively small, not conspicuous and has four pieces of green with yellow petals. About 20 small flowers densely arrange them to form a round umbel in the middle which is surrounded by four pieces of conspicuous white, pink or red bracts.
【汉译英 Chinese to English】
山茱萸的花朵单个较小且不显眼，具有四片绿色带黄色的花瓣（不是苞片）。大约有20朵小花密集地排列成一个圆形伞状的花序。这个中央的花序被四片显眼的白色、粉色或红色的大苞片（不是花瓣）所包围。
Notes:
(1) 现在正是山茱萸树(flowering dogwood)开花的时候，有白色的，粉色的，和红色的，大大的一树花，很显眼好看。
(2) 中国也有山茱萸树，花期比北美的要晚一个月。
(3) 王维的诗，“遥知兄弟登高处，遍插茱萸少一人”，诗里的茱萸据考证不是山茱萸，而是吴茱萸，很不一样的树。
下面是作者社区里拍的正开花的一株山茱萸树
山茱萸的花朵单个较小且不显眼，具有四片绿色带黄色的花瓣（不是苞片）。大约有20朵小花密集地排列成一个圆形伞状的花序。这个中央的花序被四片显眼的白色、粉色或红色的大苞片（不是花瓣）所包围。
1. An individual flowering dogwood is small and inconspicuous, with four greenish-yellow petals. Densely clustered in its center are about 20 tiny flowers in a round umbrella-shaped inflorescence, (which are) surrounded by four noticeable bracts that are white, pink or red in color.
2. An individual flowering dogwood is small and inconspicuous, with four greenish-yellow petals, in the center of which clustered twentyish tiny flowers in a round umbrella-shaped inflorescence, surrounded by four noticeable bracts that are white, pink or red in color.
An Individual flower of a flowering dogwood is relatively small, not conspicuous and has four pieces of green with yellow petals. About 20 small flowers densely arrange them to form a round umbel in the middle which is surrounded by four pieces of conspicuous white, pink or red bracts.
好久没有在诗坛看见你的诗词了。
"An individual flowering dogwood" 说成"An individual dogwood flower"更准确些。"in the center of which"和"in its center", 感觉原文并没有这个意思。
只有花序没有译出来，可以稍改一下就可以了：form a round umbel-shaped inflorescence.
图片来自网络：
不过一朵虞美人花有四片大红花瓣，而山茱萸其实是四个大的苞片围着二十来朵小花组成的花序。下面的近景图片是网上找的