r species. Phytoneuron 2012-95:
Superintendent, Greenspace Management
COH Parks and Recreation
2999 South Wayside Drive
Houston, Texas 77023
Two non-native plant species are first reported here as growing outside of cultivation in
Harris Co., Texas, and are additions to the non-native flora of Texas. Gilia tricolor has been
introduced as a wildflower along the ditches in parts of the Westchase area of Houston and
Macroptilium lathyroides has been found growing in landscapes in association with nursery plants
originating in Florida. Ludwigia peruviana has been found naturalized in the Houston area, only the
second county record from Texas. Manihot grahamii, previously mis identified as M. esculenta, also
is a naturalized species in southeast Texas, documented here from Hardin and Harris counties.
Gilia tricolor Benth. (Polemoniaceae) was a very common wildflower species in a ditch near the
Westchase area of Houston, apparently glowing from seeds sown in late 2009. The site was visited
the next two years and seedlings were observed, but it was not visited again, to see if the plants were
flowering. The species is native to California and also known to be naturalized in Colorado and
Massachusetts (BONAP 2012). There are no Gilia species known from southeast Texas (Correll &
Johnston 1970; Hatch et al. 1990). This species is characterized by its tricolor corolla; yellow with
purple spots below the blue-violets lobes (Fig. 1). It is the first member of Polemoniaceae to be
added to the list of non-native plants of Texas (Nesom et al. 2010; Aplaca 2010).
Harris Co. : Houston, Westchase area, growing alongside ditch behind the Robinson Library all the way
to and past Walnut Bend; Key Map 489 Y; with Lupinus, Bromus, Lolium, Phlox, all possibly seeded, 19 Apr
2010, Aplaca 790 (SBSC, SWT).
Macroptilium lathyroides (L.) Urfo. (Fabaceae) (wild bushbean) is growing prolifically in a library
landscape in West Houston. The plants have been observed freezing back to the ground in the winter
of 2010-11 and new plants sprouted in the summer of 2011. These plants were not planted in the
landscape; therefore the seeds must have arrived in the soil on the landscaped plants. This species is
native to tropical America and is naturalized in Florida, Georgia, Louisiana, and South Carolina
(USDA, NRCS 2012). Many of the landscape plants originated in Florida (pers. comm., K. Asakura,
Asakura-Robinson .Landscaping), where the seeds were probably stowaways in the soil. Landscape
maintenance has tried to control this plant by hand removal but it readily reseeds.
Wild bushbean is a twining herbaceous annual up to 1.5 meters (Fig. 2). The flowers are
scarlet to purple red with a spirally twisted keel and the legume is linear, straight and mostly 8-12 cm
long, ca. 3 mm wide (Fig. 3). The spiraled leaves are pinnate trifoliolate, leaflets ovate or elliptical,
2-4 cm long and 1.5-3.5 cm wide. The individuals in this population showed variety between ovate
and elliptical leaflets. The landscape maintenance has tried to control this plant, but it readily reseeds.
Harris Co. : Houston, growing in the landscape of the new Kendall Library/Community Outer on
Eldridge Pkwy just N of Buffalo Bayou, large plants ascending and twining through other vegetation; Key Map
488G; glowing near the bases of various grasses and Crinum in the landscape, obviously an introduction from
nursery contamination, 6 Aug 2010, Aplaca 832 (SBSC, SWT).
Aplaca: Texas non-natives 2
Figure 1. Gilia tricolor in Harris County.
Figure 3. Macroptilium laihyroides flowers and fruit.
Aplaca: Texas non-natives 4
Ludwigia peruviana (L.) H. Hara (Onagraceae) (Peruvian primrose-willow) is a woody species that
has previously only been recorded from Terrell County in west Texas (Ramamoorthy & Zardini
1987). In 2008 the author found a population thriving in a wetland area of Hermann Park in Houston.
There were several shrubs about 2.5 m tall and the plants were observed spreading over the following
several years. This is the first record in Texas outside the single collection from Terrell County. The
area of Hermann Park is generally left to grow naturally with little maintenance by the park staff.
There has been no attempt to control these plants, but concerns about potential invasiveness have
been brought up to the Hermann Park Conservancy and the Houston Parks Department.
Figure 5. Ludwigia peruviana growth habit of an individual 1 5 meters from the original population.
Aplaca: Texas non-natives
Manihot grahamii Hook. (Euphorbiaceae) (Graham's manihot) was collected from sites in Hardin
and Hams counties. Many of these vouchers were previously identified as M. esculenta Crantz and
have been correctly annotated by (pers. comm, Dr. J. Hayden, University of Richmond). The earliest
voucher reports this species as cultivated at the Houston Arboretum in Harris County in 1 976. It has
been reported from Florida, Georgia, and Louisiana (USD A, NRCS 2012; BONAP 2012) but not
previously from Texas. The vouchers cited here apparently have been the basis for attributions of M.
esculenta to the Texas flora.
Manihot grahamii is a South American species that is known to be more cold tolerant than
others. The plants become small trees in understory areas and spread regularly from seed and
vegetative growth. The area in Harris County has been observed for about a year and a half — the
plants are behind the city greenhouse spreading into the forested areas of Memorial Park. The extent
of the invasiveness of this species is not known yet, but when the area was cleared of some of the
larger individuals, seedlings and root sprouts were actively growing soon afterwards.
Figure 6 - Manihot grahamii individual in Memorial Park, Harr:
Hard in Co. : near Evadale Bridge E of Silsbee and S of highway, ca 50 plants in garbage dump area W
side of Neches River; seemingly well established in wild, 24 Aug 1983, Johnston 12800 (TEX). Harris Co. :
Houston Arboretum, cultivated in Houston, 1976, Vines s.n. (SBSC); banks of Buffalo Bayou, across from
Houston Arboretum, Houston, Apr 1976, Anderson s.n. (SBSC); Houston, plant grown from seed obtained in
Mexico; fairly large tree in backyard flowerbed, 2.5-3" diameter trunk, 10231 Ivy Ridge, home of Mr. & Mrs.
Doug Williams, IS May 1 992, TvetenL-1498 (SBSC); tall shrub near- Cypress Creek in Mercer Arboretum and
Botanical Gardens along Aldine Westfield Rd, N of Hwy I960 and on S side of Cypress Creek, N of Houston,
25 Oct 1997, Brown 21668 (SBSC); Magnolia Gardens, 2.4 Oct 2002, Johnson 1193 (SBSC); Houston, behind
HPAKD greenhouse at 6502 Memorial Drive, spreading into Memorial Park; 1 9 Jun 2009, Aplaca 667 (SBSC).
Aplaca, J. 2010. The Non-Native Flora of Texas. Theses and Dissertations-Biology. Paper 30.
Correll, D.S. and M.C. Johnston. 1970. Manual of the Vascular Plants of Texas. Texas Research
Hatch, S.L., K.N. Gandhi, and L.E. Brown. 1990. Checklist of the Vascular Plants of Texas. Texas
Agricultural Experiment Station, College Station.
Jones, S.D., J.K. Wipff, and P.M. Montgomery. 1997. Vascular Plants of Texas: A Comprehensive
Checklist Including Synonomy, Bibliography and Index. Univ. of Texas Press, Austin.
BONAP. 2012. North American Plant Atlas (US county-level species maps). Biota of North
America Program, Chapel Hill, North Carolina. Last update: Oct 2011
Nesom, G.L., J.L. Aplaca. W.R. Carr, N.L. Fowler, L.L. Hansen, S.L. Hatch, B.W. Hoagland, W.C.
Holmes, E.L. Keith, B.L. Lipscomb, B.R MacRoberts, M.H. MacRoberts, J. A. McDonald,
T.F. Patterson, J.M. Poole, AM. Powell, N. Rich, M.D. Reed, D.J. Rosen, J.R. Singhurst,
B.A. Sorrie, B.L. Turner, D.E. Waitt, and J.K. Williams. 2010. Texas non-native plants:
Overview of occurrence and invasiveness assessments, <http://www.texasnonnatives.org>
Ramamoorthy T.P. and E.M. Zardini. 1987. The systematics and evolution of Ludwigia sect.
Myrtocarpus sensu lato (Onagraceae). Syst. Bot. Monogr. 19: 1-120.
USDA NRCS. 2012. The PLANTS Database. National Plant Data Team, Greensboro, North