Ask Mr. Smarty Plants

When I first read your question I thought to myself:  "I didn't know that. I think I better check several sources to confirm that  Prunus minutiflora (Dwarf plum or Texas almond) is dioecious, i.e., with male and female flowers on different plants."  I found the Aggie-Horticulture site that says:  "It is dioecious, that is, male and female flowers are on separate plants.  Apparently, staminate (male) plants are more numerous than the pistillate (female)."   Next I thought I should also check this statement in Correll and Johnston.  1979.  Manual of the Vascular Plants of Texas.   Things got a little confusing when I read that they wrote that all Prunus species have "perfect flowers", i.e., they have both stamens (male parts) and pistils (female parts).  They do say that the flowers have numerous stamens, but there is only one pistil per flower.  I could not find information in any of the other numerous print sources that I have for Texas plants that the tree is dioecious so I assumed that the Aggie-Horticulture site was in error.   I decided to check with our staff authority, Joe Marcus, who provided the following reference:  THE PUBESCENT-FRUITED SPECIES OF PRUNUS OF THE SOUTHWESTERN STATES by Silas C. Mason in The Journal of Agricultural Research (1913) vol. 1, no. 2.  On page 152 of this paper Mason states that three of the Prunus spp. discussed in paper [Prunus fasciculata (Desert almond), Prunus microphylla (Mexican wild almond) and Prunus minutiflora (Dwarf plum)] share the following feature which makes them dioecious (male and female flowers on separate plants):

"The California desert almond (Prunus fasciculata), the Texas wild
almond (P. minutiflora), and the Mexican wild almond (P. microphylla),
agree in three important characters which separate them clearly from
the three other species of this group. All three are dioecious by the abortion
of either stamens or pistils; the number of the stamens is usually
reduced to 10 or 15 and a portion of them inserted on the walls of the
calyx cup."

So, even though the flowers have the potential to be perfect flowers, either the stamens or the pistil of the flower becomes non-functional so that each individual plant has all its flowers functioning as males or all its flowers functioning as females.

On page 174 you will find a description of the botanical characteristics of Prunus minutiflora that includes this statement:

"The minute flowers, borne singly or paired, on short peduncles, are usually crowded
on short, budlike fruiting spurs. They appear with the leaves in February or March
and are minute and dioecious by the abortion of the stamens in the fruiting form and
of the pistils in the opposite form."

On page 173 of this paper you can see line drawings of both pistillate flowers and staminate flowers of P. minutiflora.    By comparing the drawings to the flowers on your tree you should be able to determine if your tree is male or female.  Unfortunately, that is the only way I know that you will be able to tell unless your tree has recently borne fruit—in that case, it is definitely a female.

In the two photos that we have showing flowers of P. minutiflora in our Image Gallery (see below) you can see the many stamens, but there are NO pistils to be seen.  This is easier to see if you can zoom in on the flowers in the photos.  I did search the internet for photos of female flowers of P. minutiflora, but could find none.