What is Torrey’s surf grass, truly? Well, for starters, it’s a monocot (meaning that it only has one seed leaf, or cotyledon when it grows), and this particular brand of surf grass is found only on the western coast of North America from Baja California, Mexico to as far north as British Columbia, Canada. To look at it, this surf grass is bright green with thin, long blades of grass, and it grows up to 2 meters long. It usually lives in the rocky intertidal, as deep as 15 meters but typically only going as deep as 5 meters.
Anyway, the interesting thing about Torrey’s surf grass (among many other interesting things) is related to sex. Isn’t it always with these surf grasses? But in all seriousness, most of the scientific literature that I came across regarding Torrey’s surf grass was centered around the idea that there is a phenomenon of male rarity among Torrey’s surf grass that is detrimental to their reproductive ability. In fact, Torrey’s surf grass is unusual because usually when there is a disparity between the genders in plants, it’s usually a lack of females that is the problem. Because Torrey’s surf grass is an obligate outcrossing species, the idea that there aren’t enough males is troubling. Outcrossing species are species that cannot self-reproduce or reproduce with individuals that are closely related to them. In other words, no self-fertilization and no plant incest. This places a lot of pressure on a successful mating, and the idea of there being too few males is not great for reproduction. Torrey’s surf grass is an extremely localized reproducer, which means that there isn’t much chance of fertilization from males not in the immediate vicinity. In fact, if a male is not within tens of meters of a female, the female will most likely lead a tragically childless life. All is not lost for the ladies though- some evidence exists that in areas of extreme male rarity, there will occasionally be fertilization events outside of the immediate vicinity, which can reduce habitat fragmentation and encourage colonization of available habitat.
It is considered to be a dioecious plant, meaning that it has plants that are specifically male or female. Hence the lack of self-fertilization ability. These specifically male or female plants are identifiable as such because they have sexually dimorphic flowers, which are found on their multiple spadices (Torrey’s surf grass usually has 5 of them). Flowering buds are typically seen in late spring, and the pollination season runs from early summer to early fall.
For the lucky ladies that do happen to get fertilized, fruit production usually occurs for 3 months throughout the summer, and seed dispersal is completed by mid-fall. As mentioned before, this species tends to favor rocky areas that are exposed to high wave energy levels, which is uncommon among most species of seagrass which prefer calmer waters in estuaries and bays. It is thought that wave activity may play an active role in the pollen transport of this species.
Phyllospadix torreyi is considered to be a foundation species for the rocky intertidal habitat. It provides shelter for many invertebrates, and supports many species of algae. It is also well-known for being a nursery habitat for young fish and invertebrates, also serving as a food source for many species such as abalone. One final note: this species is pretty resilient in the face of disturbance on the condition that its rhizome remains viable, but it is sensitive to some forms of pollution and also desiccation. All in all, not bad for a male-deprived population of seagrass plants.
Buckel, C. A., Blanchette, C.A., Warner, R.R., and S.D. Gaines. 2012. Where a male is hard to find: consequences of male rarity in the surfgrassPhyllospadix torreyi. Marine Ecology Progress Series 449: 121-132
Shelton, A. O. 2008. Skewed Sex Ratios, Pollen Limitation, and Reproductive Failure in the dioecious seagrass Phyllospadix torreyi. Ecology 89:3020-3029
Phillips RC (1979) Ecological notes on Phyllospadix (Potamogetonaceae)
in the Northeast Pacific. Aquatic Botany 6:159−170