Underutilized Native Woody Legumes for Landscape Use

Item Type text; Article

Authors Johnson, M. B.; Palzkill, D. A.

Publisher College of Agriculture, University of (Tucson, AZ)

Journal Turfgrass and Ornamentals Research Summary

Download date 29/09/2021 16:32:23

Link to Item http://hdl.handle.net/10150/216072 Underutilized Native Woody Legumes For Landscape Use

M. B. Johnson and D. A. Palzkill

INTRODUCTION

Many speciesofplantsnativetotheSonoranDesertregionhavenotbeenextensively evaluatedfortheirlandscapepotential. Often,plantshavebeengrownandevaluatedona limitedscalebuttheinformation has not been published orisdispersedthroughtheliterature. The lackof awarenessof plantswith landscapepotential and thelackofaccessibleinformation about them contributes to their limited availability and use.

Treesandshrubsofthepeafamily(Leguminosae)areaconspicuousfeatureofthe vegetation of much of the region.These have several features which make them good candidates forusein landscaping inaridregions. Legumes are able tofixnitrogen, minimizingtheirneedfor expensivefertilizers. Theytoleratehottemperaturesand low humidity. Onceestablished,theyareabletosurviveforlongerperiodswithoutirrigation than many traditional landscape plants from less arid regions.

Sevenspeciesof leguminoustreesand shrubs havepotentialforwider useaslandscape plantsare:Coursetiaglandulosa,Erythrinaflabelliformis,Eysenhardtiaorthocarpa, Haematoxylon brasiletto, Lysilomawatsonii. Pithecellobiummexicanum,andSophoraarizonica. An attempt was made to gatherallavailable information on thesespecies concerning methods of propagation, cultural aspects in the landscape and landscape potential (1). Coursetia glandulosa (Baby Bonnets) is a medium to large shrub, 2 to 4 m tall and broad. Typicallymultiplestemmed andratheropen,ithasdeciduousgray -greenfoliageandproduces small flowersthatare yellow and white with pink markings. The plantiseasily propagated by usingscarifiedseed. Growthratesaremoderateifsupplementalirrigationisprovided. C. glandulosaishardyto-6.5° C (20°F.). No significantpestordiseaseproblems have been reported. It can be used as a background or accent or as an informal screen. Plants may be observed near the entrance to the Earth Science Cave at the Arizona Desert Museum.

Erythrinaflabelliformis(Southwest Cr raiBean) growsasamultiple stemmed shrubto2 m tallin areas that experience freezing temperatures. It can develop into a small tree in warm areas and protectedsites. Bright green,deciduous leaves are produced inthe summer following theattractivescarletflowers. Theplantiseasilypropagatedusingscarifiedseedorstem cuttings. E flabelliformishas a moderate growth rate when givensupplementalirrigation. The stems will freeze at-2.2°to -4.4° C (28°to 24°F). The plant has no serious pest or disease problems incultivationinsouthern Arizona. Ithas some potentialfor useinlandscapes as an accent or background plant oras a specimen or small patiotreein warmer areas. The showy flowersattracthummingbirds. The scarletseedsarereportedto behighlypoisonousifeaten. CultivatedplantsarelocatedintheAviaryandintheDemonstration GardenattheArizona Sonora Desert Museum and in the Demonstration Garden at Tohono Chul Park in Tucson.

109 orthocarna (Kidneywood) is an upright shrub i to 4 m tall or a small tree to 6 m tall. Itiscold and droughtdeciduous.Attractiveinflorescencesofsmall,fragrantwhite flowers are produced in the spring and summer.The plant may be propagated by seed and by cuttings;theseedwillgerminatewithoutscarification. Growthisrapidinacontainerorin the ground with supplemental irrigation. . orthocarpa is hardy toatleast -6.5° C (20°F). No pest or disease problems have been reported.The plant is suitable as a small patio tree due toitsupright form;itcan be used as a background plant or providea vertical elementina landscape. Cultivated plants may be seen near the Demonstration Garden and in the Entry Plaza area at Tohono Chul Park in Tucson and in the wildflower garden at the Tucson Botanical Gardens.

Haematoxylon brasiletto(Brasilwood) growsasa multiple stemmed shrub orsmalltree4 to 6 m tall.The growth form is usually upright and dense.Young stems are zig -zag with a thorn ateach node. The older stemsofthisplantareunique;they developirregularflutedridges and furrowsgivingthestemsabuttressedappearance. Theattractiveheart- shapedleafletsare cold and drought deciduous. Clusters of bright yellow flowers appear in the summer and autumn oncultivatedplantsinsouthernArizona. Plantswillgrowreadilyfromscarifiedseed;the growthrateismoderateinthelandscapewithsupplementalirrigation. H brasilettowill suffer freeze damage at-4.4°to -5.5° C (24 to 22°F), but recovery israpid in the spring. No pest or disease problems have been reported. The plantissuitable as a small patio tree in warm areas where it can be pruned to reveal the fluted stems.It can be used as a background, accent or specimen plant.Cultivated plants may be observed in the Demonstration Garden at the Arizona Sonora Desert Museum, the Demonstration Garden at Tohono Chul Park and at the Desert Botanical Garden in Phoenix. Lysiloma watsonii (Feather Tree) grows as a dense shrub to 2 m tall in cold sites but will develop into a spreading tree to 6 or 8 m tall in warm areas of southern Arizona. The graceful, feathery,blue -greenfoliagecontrastswellwiththebrownbark;theleavesareretainedin mild winters. Fragrant, cream coloredclustersof flowersare produced inprofusioninthelate spring. Scarified seeds germinate readily. The plant has a moderate tofast rate of growth when given supplemental irrigation. L watsonii will begin tosuffer freeze damage at-4° C (25°F), but recovery israpid in the spring. No significantpest or disease problems have been reported. Theplantlendsatropicaleffecttoalandscape,andissuitableintransitionalplantingsand asapatiotree. The densefoliageiseffectiveasascreen. Incolderareasitmakes an attractive summer shrub. Cultivated plants may be seen atbotanical gardens in southern Arizona and in landscapes in Phoenix and Tucson.

Pithecellobiummexicanum(MexicanEbony)isasymmetrical,high- canopiedtreegrowing to 10 or occasionally 15 m tall.The thin twigs bear a pair of small thorns at each node. The deciduous foliage is gray - green, andattractive, fragrant, cream colored flower headsare producedinthespring. Scarifiedseedgerminatesrapidly;thegrowthisveryfastwith supplementalirrigationingoodsoil. The plantdoesnot grow wellinrockysoilorcaliche; however,alargeholeback -filledwithcleanfillalleviatesthisproblem. mexicanumis hardy to at least -8° C (18°F). No pests have been reported.The upright growth habit of this plant makesitidealfor use as astreettreeor as a yard or patiotree. The foliagecastsa light,filteredshade. Cultivatedplants may be seen near the parkinglotsoutheast of theold visitorcenteratthe Boyce Thompson Southwestern Arboretum, behind the Webster Auditoriumat the Desert Botanical Garden, and in the Demonstration Garden at Tohono Chul Park.

Sophora arizomea (Arizona Sophora)isa dense, rounded, evergreen shrub 2 to 3 m tall. Thefoliageisanattractiveblue -greencolor. Dense massesoffragrant,lavendertopurple flowersare produced in March and April. The plant may be grown fromscarifiedseed,but cuttingsrootwithdifficulty. Very highmortalityofseedlingsand youngplantsincontainers frequentlyoccurs. Usingsoilfrom areas where theplantsnaturallyoccurinthesoilmix has produced encouraging results. Growth is slow and good drainage is necessary.

110 arizonicaishardy toatleast -17.7° C (0°F). The plantisoccasionally infested by the pyralidmothleafcaterpillar. Plantsincontainersarefrequentlykilledbyrootrotfungi. arizonicaisa beautifulplantand would make anattractivelandscapeplantifa dependable method of propagation can be developed.It can be used as a screen or informal hedge, or as a specimen plant. The orange -redseeds are reported to be poisonous. Cultivatedplants may be seen on the west side of the Friend's House at the Tucson Botanical Gardens. REFERENCES

1. Johnson, M. B.1988. Horticultural characteristics of seven Sonoran Desert woody legumes withpotentialforlandscapingintheSouthwest. M.S.Thesis. TheUniversityofArizona, Tucson, Arizona. In preparation.

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